pax_global_header00006660000000000000000000000064147636461600014527gustar00rootroot0000000000000052 comment=d3394b1da036ddb6aa6f322413ad9135d7942333 didder-1.3.0/000077500000000000000000000000001476364616000127635ustar00rootroot00000000000000didder-1.3.0/.github/000077500000000000000000000000001476364616000143235ustar00rootroot00000000000000didder-1.3.0/.github/FUNDING.yml000066400000000000000000000000431476364616000161350ustar00rootroot00000000000000github: makew0rld ko_fi: makeworld didder-1.3.0/.github/workflows/000077500000000000000000000000001476364616000163605ustar00rootroot00000000000000didder-1.3.0/.github/workflows/goreleaser.yml000066400000000000000000000010041476364616000212260ustar00rootroot00000000000000name: goreleaser on: push: tags: - v* jobs: goreleaser: runs-on: ubuntu-latest steps: - name: Checkout uses: actions/checkout@v2 with: fetch-depth: 0 - name: Set up Go uses: actions/setup-go@v2 with: go-version: 1.21 - name: Run GoReleaser uses: goreleaser/goreleaser-action@v2 with: version: 0.x args: release --rm-dist env: GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }} didder-1.3.0/.github/workflows/test.yml000066400000000000000000000013441476364616000200640ustar00rootroot00000000000000name: test on: push: paths-ignore: - "**.md" - "LICENSE" - "didder.1" pull_request: paths-ignore: - "**.md" - "LICENSE" - "didder.1" jobs: test: runs-on: ubuntu-latest strategy: fail-fast: false matrix: go-version: ["1.20", "1.21"] steps: - name: Install Go uses: actions/setup-go@v2 with: go-version: ${{ matrix.go-version }} - name: Checkout code uses: actions/checkout@v2 - uses: actions/cache@v2 with: path: ~/go/pkg/mod key: ${{ runner.os }}-go-${{ hashFiles('**/go.sum') }} restore-keys: | ${{ runner.os }}-go- - name: Test run: make didder-1.3.0/.gitignore000066400000000000000000000033631476364616000147600ustar00rootroot00000000000000NOTES.md *.png *.gif didder didder-* !david_dithered.png # Created by https://www.toptal.com/developers/gitignore/api/go,code,linux,windows,macos # Edit at https://www.toptal.com/developers/gitignore?templates=go,code,linux,windows,macos ### Code ### .vscode/* !.vscode/tasks.json !.vscode/launch.json *.code-workspace ### Go ### # Binaries for programs and plugins *.exe *.exe~ *.dll *.so *.dylib # Test binary, built with `go test -c` *.test # Output of the go coverage tool, specifically when used with LiteIDE *.out # Dependency directories (remove the comment below to include it) # vendor/ ### Go Patch ### /vendor/ /Godeps/ ### Linux ### *~ # temporary files which can be created if a process still has a handle open of a deleted file .fuse_hidden* # KDE directory preferences .directory # Linux trash folder which might appear on any partition or disk .Trash-* # .nfs files are created when an open file is removed but is still being accessed .nfs* ### macOS ### # General .DS_Store .AppleDouble .LSOverride # Icon must end with two \r Icon # Thumbnails ._* # Files that might appear in the root of a volume .DocumentRevisions-V100 .fseventsd .Spotlight-V100 .TemporaryItems .Trashes .VolumeIcon.icns .com.apple.timemachine.donotpresent # Directories potentially created on remote AFP share .AppleDB .AppleDesktop Network Trash Folder Temporary Items .apdisk ### Windows ### # Windows thumbnail cache files Thumbs.db Thumbs.db:encryptable ehthumbs.db ehthumbs_vista.db # Dump file *.stackdump # Folder config file [Dd]esktop.ini # Recycle Bin used on file shares $RECYCLE.BIN/ # Windows Installer files *.cab *.msi *.msix *.msm *.msp # Windows shortcuts *.lnk # End of https://www.toptal.com/developers/gitignore/api/go,code,linux,windows,macos didder-1.3.0/.goreleaser.yml000066400000000000000000000014321476364616000157140ustar00rootroot00000000000000project_name: didder env: - GO111MODULE=on before: hooks: - go mod download builds: - env: - CGO_ENABLED=0 goos: - linux - windows - darwin - freebsd - netbsd - openbsd goarch: - 386 - amd64 - arm64 - arm goarm: - 6 - 7 ignore: - goos: darwin goarch: 386 - goos: freebsd goarch: arm - goos: freebsd goarch: arm64 - goos: netbsd goarch: arm - goos: netbsd goarch: arm64 - goos: openbsd goarch: arm - goos: openbsd goarch: arm64 archives: - format: binary replacements: darwin: macOS 386: 32-bit amd64: 64-bit milestones: - close: true changelog: skip: true didder-1.3.0/CHANGELOG.md000066400000000000000000000016211476364616000145740ustar00rootroot00000000000000# Changelog All notable changes to this project will be documented in this file. The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/), and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html). ## [1.3.0] - 2022-12-20 ## Changed - Updated dither library to v2.4.0 - Increased error diffusion dithering speed by ~50% - Reduced error diffusion dithering memory usage by ~70% (#13) ## [1.2.0] - 2022-12-20 ### Changed - Updated dither library to v2.3.0 - When comparing colors, each channel is weighted according to human luminance perception (#14) ### Fixed - Updated dither library to v2.3.0 - Corrected Burkes matrix (dither#10) - Palette order no longer affects output (dither#9) ## [1.1.0] - 2021-05-09 ### Added - Support for transparent images (#1) - `--recolor` can handle RGB**A** colors (#1) ## [1.0.0] - 2021-05-01 Initial release. didder-1.3.0/LICENSE000066400000000000000000001045151476364616000137760ustar00rootroot00000000000000 GNU GENERAL PUBLIC LICENSE Version 3, 29 June 2007 Copyright (C) 2007 Free Software Foundation, Inc. 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But first, please read . didder-1.3.0/MANPAGE.md000066400000000000000000000367221476364616000143670ustar00rootroot00000000000000 --- title: DIDDER section: 1 header: User Manual footer: didder v1.3.0 date: December 20, 2023 --- # NAME didder — dither images # SYNOPSIS **didder** \[global options] command [command options] [arguments...] # DESCRIPTION Dither images with a variety of algorithms and processing options. Images with transparency are supported, and their alpha channel is kept the way it was to begin with. Mandatory global flags are **\--palette**, **\--in**, and **\--out**, all others are optional. Each command applies a dithering algorithm or set of algorithms to the input image(s). The most important parts of this manual are highlighted in the **TIPS** section, make sure you check it out! Homepage: # OPTIONS **-i**, **\--in** *PATH* Set the input file. This flag can be used multiple times to dither multiple images with the same palette and method. A *PATH* of \'**\-**' stands for standard input. The input file path can also be parsed as a glob. This will only happen if the path contains an asterisk. For example **\-i \'\*.jpg'** will select all the .jpg files in the current directory as input. See this page for more info on glob pattern matching: **-o**, **\--out** *PATH* Set the output file or directory. A *PATH* of \'**\-**' stands for standard output. If *PATH* is an existing directory, then for each image input, an output file with the same name (but possibly different extension) will be created in that directory. If *PATH* is a file, that ends in .gif (or **\--format gif** is set) then multiple input files will be combined into an animated GIF. **-p**, **\--palette** *COLORS* Set the color palette used for dithering. Colors are entered as a single quoted argument, with each color separated by a space. Colors can be formatted as RGB tuples (comma separated), hex codes (case-insensitive, with or without the '#'), a single number from 0-255 for grayscale, or a color name from the SVG 1.1 spec (aka the HTML or W3C color names). All colors are interpreted in the sRGB colorspace. A list of all color names is available at Images are converted to grayscale automatically if the palette is grayscale. This produces more correct results. Here's an example of all color formats being used: **\--palette \'23,230,100 D24242 135 forestGreen'** **-r**, **\--recolor** *COLORS* Set the color palette used for replacing the dithered color palette after dithering. The argument syntax is the same as **\--palette**, with one exception. It also supports RGB*A* tuples, so 4 values. This means you can also choose to change the opacity of a palette color after dithering. The values are not premultiplied, so set the RGB to the color you want as you'd expect. The **\--recolor** flag exists because when palettes that are severely limited in terms of RGB spread are used, accurately representing the image colors with the desired palette is impossible. Instead of accuracy of color, the new goal is accuracy of luminance, or even just accuracy of contrast. For example, the original Nintendo Game Boy used a solely green palette: . By setting **\--palette** to shades of gray and then **\--recolor**-ing to the desired shades of green, input images will be converted to grayscale automatically and then dithered in one dimension (gray), rather than trying to dither a color image (three dimensions, RGB) into a one dimensional green palette. This is similar to "hue shifting" or "colorizing" an image in image editing software. For these situations, **\--recolor** should usually be a palette made up of one hue, and **\--palette** should be the grayscale version of that palette. The **\--palette** could also be just equally spread grayscale values, which would increase the contrast but make the luminance inaccurate. Recoloring can also be useful for increasing contrast on a strange palette, like: **\--palette \'black white' \--recolor \'indigo LimeGreen'**. Setting just **\--palette \'indigo LimeGreen'** would give bad (low contrast) results because that palette is not that far apart in RGB space. These "bad results" are much more pronounced when the input image is in color, because three dimensions are being reduced. **-s**, **\--strength** *DECIMAL/PERCENT* Set the strength of dithering. This will affect every command except **random**. Decimal format is -1.0 to 1.0, and percentage format is -100% or 100%. The range is not limited. A zero value will be ignored. Defaults to 100%, meaning that the dithering is applied at full strength. Reducing the strength is often visibly similar to reducing contrast. With the **edm** command, **\--strength** can be used to reduce noise, when set to a value around 80%. When using the **bayer** command with a grayscale palette, usually 100% is fine, but for 4x4 matrices or smaller, you may need to reduce the strength. For **bayer** (and by extension **odm**) color palette images, several sites recommend 64% strength (written as 256/4). This is often a good default for **bayer**/**odm** dithering color images, as 100% will distort colors too much. Do not use the default of 100% for Bayer dithering color images. **-j**, **\--threads** *NUM* Set the number of threads used. By default a thread will be created for each CPU. As dithering is a CPU-bound operation, going above this will not improve performance. This flag does not affect **edm**, as error diffusion dithering cannot be parallelized. **-g**, **\--grayscale** Make input image(s) grayscale before dithering. **\--saturation** *DECIMAL/PERCENT* Change input image(s) saturation before dithering. Decimal range is -1.0 to 1.0, percentage range is -100% or 100%. Values that exceed the range will be rounded down. -1.0 or -100% saturation is equivalent to **\--grayscale**. **\--brightness** *DECIMAL/PERCENT* Change input image(s) saturation before dithering. Decimal range is -1.0 to 1.0, percentage range is -100% or 100%. Values that exceed the range will be rounded down. **\--contrast** *DECIMAL/PERCENT* Change input image(s) saturation before dithering. Decimal range is -1.0 to 1.0, percentage range is -100% or 100%. Values that exceed the range will be rounded down. **\--no-exif-rotation** Disable using the EXIF rotation flag in image metadata to rotate the image before processing. **-f**, **\--format** *FORMAT* Set the output file format. Valid options are \'png' and \'gif'. It will auto detect from filename when possible, so usually this does not need to be set. If **-o** is \'**-**' or a directory, then PNG files will be outputted by default. So this flag can be used to force GIF output instead. If your output file has an extension that is not .png or .gif the format will need to be specified. **\--no-overwrite** Setting this flag means the program will stop before overwriting an existing file. Any files written before that one was encountered will stay in place. **-c**, **\--compression** *TYPE* Set the type of PNG compression. Options are \'default', \'no', \'speed', and \'size'. This flag is ignored for non-PNG output. **\--fps** *DECIMAL* Set frames per second for animated GIF output. Note that not all FPS values can be represented by the GIF format, and so the closest possible one will be chosen. This flag has no default, and is required when animated GIFs are being outputted. This flag is ignored for non animated GIF output. **-l**, **\--loop** *NUM* Set the number of times animated GIF output should loop. 0 is the default, and will loop infinitely. **-x**, **\--width** *NUM* Set the width the input image(s) will be resized to, before dithering. Aspect ratio will be maintained if **\--height** is not specified as well. **-y**, **\--height** *NUM* Set the height the input image(s) will be resized to, before dithering. Aspect ratio will be maintained if **\--width** is not specified as well. **-u**, **\--upscale** *NUM* Scale image up after dithering. So \'2' will make the output two times as big as the input (after **-x** and/or **-y**). Only integers are allowed, as scaling up by a non-integer amount would distort the dithering pattern and introduce artifacts. **-v**, **\--version** Get version information. # COMMANDS **random** *MIN MAX* or *RED_MIN RED_MAX GREEN_MIN GREEN_MAX BLUE_MIN BLUE_MAX* Grayscale and RGB random dithering Accepts two arguments (min and max) for RGB or grayscale, or six (min/max for each channel) to control each RGB channel. Arguments can be separated by commas or spaces. Random dithering adds random noise to the image. The min and max numbers limit the range of the random noise. A good default is -0.5,0.5, which means that a middle gray pixel is 50% likely to become black and 50% likely to become white, assuming a black and white palette. So -0.2,2.0 will reduce the noise (20%), while -0.7,0.7 will increase it (70%). Values like -0.5,0.7 will bias the noise to one end of the channel(s). **-s**, **\--seed** *DECIMAL* Set the seed for randomization. This will also only use one thread, to keep output deterministic. By default a different seed is chosen each time and multiple threads are used. **bayer** *X* *Y* Bayer matrix ordered dithering Requires two arguments, for the X and Y dimension of the matrix. They can be separated by a space, comma, or \'x'. Both arguments must be a power of two, with the exception of: 3x5, 5x3, and 3x3. **odm** *NAME/JSON/FILE* Ordered Dithering Matrix Select or provide an ordered dithering matrix. This only takes one argument, but there a few types available: - A preprogrammed matrix name - Inline JSON of a custom matrix - Or a path to JSON for your custom matrix. \'**-**' means standard input. Here are all the built-in ordered dithering matrices. You can find details on these matrices here: - ClusteredDot4x4 - ClusteredDotDiagonal8x8 - Vertical5x3 - Horizontal3x5 - ClusteredDotDiagonal6x6 - ClusteredDotDiagonal8x8_2 - ClusteredDotDiagonal16x16 - ClusteredDot6x6 - ClusteredDotSpiral5x5 - ClusteredDotHorizontalLine - ClusteredDotVerticalLine - ClusteredDot8x8 - ClusteredDot6x6_2 - ClusteredDot6x6_3 - ClusteredDotDiagonal8x8_3 Their names are case-insensitive, and hyphens and underscores are treated the same. The JSON format (whether inline or in a file) looks like the below. The matrix must be "rectangular", meaning each array must have the same length. More information how to use a custom matrix can be found here: ```json { "matrix": [ [12, 5, 6, 13], [4, 0, 1, 7], [11, 3, 2, 8], [15, 10, 9, 14] ], "max": 16 } ``` **edm** *NAME/JSON/FILE* Error Diffusion Matrix Select or provide an error diffusion matrix. This only takes one argument, but there a few types available: - A preprogrammed matrix name - Inline JSON of a custom matrix - Or a path to JSON for your custom matrix. \'**-**' means stdin. Here are all the built-in error diffusion matrices. You can find details on these matrices here: - Simple2D - FloydSteinberg - FalseFloydSteinberg - JarvisJudiceNinke - Atkinson - Stucki - Burkes - Sierra (or Sierra3) - TwoRowSierra (or Sierra2) - SierraLite (or Sierra2_4A) - StevenPigeon Their names are case-insensitive, and hyphens and underscores are treated the same. The JSON format (whether inline or in a file) for a custom matrix is very simple, just a 2D array. The matrix must be "rectangular", meaning each array must have the same length. **-s**, **\--serpentine** Enable serpentine dithering, which "snakes" back and forth when moving down the image, instead of going left-to-right each time. This can reduce artifacts or patterns in the noise. # TIPS Read about **\--strength** if you haven't already. Read about **\--recolor** if you haven't already. It's easy to mess up a dithered image by scaling it manually. It's best to scale the image to the size you want before dithering (externally, or with **\--width** and/or **\--height**), and then leave it. If you need to scale it up afterward, use **\--upscale**, rather than another tool. This will prevent image artifacts and blurring. Be wary of environments where you can't make sure an image will be displayed at 100% size, pixel for pixel. Make sure to at least use nearest-neighbor scaling, do your best to preserve sharp pixel edges. Dithered images must only be encoded in a lossless image format. This is why the tool only outputs PNG and GIF. To increase the dithering artifacts for aesthetic effect, you can downscale the image before dithering and upscale after. Like if the image is 1000 pixels tall, your command can look like **didder --height 500 --upscale 2 [...]**. Depending on the input image size and what final size you want, you can of course just upscale as well. If your palette (original or recolor) is low-spread — meaning it doesn't span much of the available shades of a single hue or the entire RGB space — you can use flags like **\--brightness**, **\--contrast**, and **\--saturation** to improve the way dithered images turn out. For example, if your palette is dark, you can turn up the brightness. As mentioned above, these flags apply their transformations to the original image and will not adjust your selected palette colors. # EXAMPLES **didder \--palette \"black white" -i input.jpg -o test.png bayer 16x16** This command dithers `input.jpg` using only black and white (implicitly converting the image to grayscale first), using a 16x16 Bayer matrix. The result is written to `test.png`. **didder \--palette \"black white" -i input.jpg -o test.png odm ClusteredDot4x4** Same command as above, but dithering with the preprogrammed ordered dithering matrix called ClusteredDot4x4. **didder -i david.png -o david_dithered.png \--palette \"black white" \--recolor \"black F273FF" \--upscale 2 bayer 4x4** This is the command used for the README. It dithers using a 4x4 Bayer matrix, initially to black and white, which is then recolored to black and purple. Dithering to black and purple directly would produce much lower contrast results. The dithered image is upscaled to be two times larger, so that the Bayer dithering artifacts can be seen more clearly. **didder -i input.png -o output.png -p \"1E1E1E CDCDCD EDEDED FFFFFF" -r \"11161e 116bcd 63b3ed e1efff" \--strength 64% \--brightness 20% bayer 32x32** This command uses a blue recolor palette, one that is biased to being darker. The palette can be viewed at . The dithering palette is the grayscale version of those colors, to keep luminance accurate. Strength is set to 64%, which although usually recommended for Bayer dithering of color images, works well here. Alternatively, one could try and increase **\--contrast**. Finally, the brightness is increased to compensate for the dark palette. **didder -p \"black white" \--recolor \"darkgreen white" -i frame_01.png -i frame_02.png -o output.gif \--fps 1 random -0.5,0.5** This command takes two input images and creates an animated GIF, dithering and recoloring them along the way. The GIF moves at 1 frame per second, and by default loops infinitely. Random dithering is used, with recommended default of -0.5,0.5. # REPORTING BUGS Any bugs can be reported by creating an issue on GitHub: didder-1.3.0/Makefile000066400000000000000000000026401476364616000144250ustar00rootroot00000000000000GITV != git describe --tags GITC != git rev-parse --verify HEAD SRC != find . -type f -name '*.go' ! -name '*_test.go' TEST != find . -type f -name '*_test.go' DATEC != date +'%B %d, %Y' PREFIX ?= /usr/local VERSION ?= $(GITV) COMMIT ?= $(GITC) BUILDER ?= Makefile DATE ?= $(DATEC) GO := go INSTALL := install RM := rm SED := sed PANDOC := pandoc GZIP := gzip MANDB := mandb CP := cp didder: go.mod go.sum $(SRC) GO111MODULE=on CGO_ENABLED=0 $(GO) build -o $@ -ldflags="-s -w -X main.version=$(VERSION) -X main.commit=$(COMMIT) -X main.builtBy=$(BUILDER)" .PHONY: clean clean: $(RM) -f didder .PHONY: man man: $(PANDOC) didder.1.md -s -t man -o didder.1 $(SED) -i 's/VERSION/$(VERSION)/g' didder.1 $(SED) -i 's/DATE/$(DATE)/g' didder.1 $(CP) didder.1.md MANPAGE.md $(SED) -i 's/VERSION/$(VERSION)/g' MANPAGE.md $(SED) -i 's/DATE/$(DATE)/g' MANPAGE.md $(SED) -i '1s/^/\n/' MANPAGE.md $(SED) -i 's/: /\n/g' MANPAGE.md $(SED) -i 's/ //g' MANPAGE.md $(SED) -i 's/^\[/ \[/g' MANPAGE.md $(SED) -i 's/\\$$//g' MANPAGE.md .PHONY: install install: didder $(INSTALL) -d $(PREFIX)/bin/ $(INSTALL) -m 755 didder $(PREFIX)/bin/didder $(GZIP) -c didder.1 > /usr/share/man/man1/didder.1.gz $(MANDB) .PHONY: uninstall uninstall: $(RM) -f $(PREFIX)/bin/didder # Development helpers .PHONY: fmt fmt: $(GO) fmt ./... didder-1.3.0/README.md000066400000000000000000000145361476364616000142530ustar00rootroot00000000000000# didder [![go reportcard](https://goreportcard.com/badge/github.com/makeworld-the-better-one/didder)](https://goreportcard.com/report/github.com/makeworld-the-better-one/didder)

didder is an extensive, fast, and accurate command-line image dithering tool. It is designed to work well for both power users as well as pipeline scripting. It is backed by my [dithering library](https://github.com/makeworld-the-better-one/dither), and is unique in its correctness and variety of dithering algorithms. No online or offline tool I know of provides as many options, while being correct (linearizing the image, weighting channels by luminance). ## Types of dithering supported - Random noise (in grayscale and RGB) - **Ordered Dithering** - Bayer matrix of any size (as long as dimensions are powers of two) - Clustered-dot - many different preprogrammed matrices - Some unusual horizontal or vertical line matrices - Yours? You can provide your own ordered dithering matrix in JSON format - **Error diffusion dithering** - Simple 2D - Floyd-Steinberg, False Floyd-Steinberg - Jarvis-Judice-Ninke - Atkinson - Stucki - Burkes - Sierra/Sierra3, Sierra2, Sierra2-4A/Sierra-Lite - [Steven Pigeon](https://hbfs.wordpress.com/2013/12/31/dithering/) - Yours? You can provide your own error diffusion matrix in JSON format More methods of dithering are being worked on, such as Riemersma, Yuliluoma, and blue noise. If you'd like to help out with development of those methods, or request a new one, please make an issue in my [dither](https://github.com/makeworld-the-better-one/dither) library repo, not this one. ## Features - Set palette using RGB tuples, hex codes, number 0-255 (grayscale), or [SVG color names](https://www.w3.org/TR/SVG11/types.html#ColorKeywords) - Optionally recolor image with a different palette after dithering - Set dithering strength - Image is automatically converted to grayscale if palette is grayscale - Force image to grayscale with `--grayscale` - Change image saturation, brightness, or contrast before dithering - Read EXIF rotation tags by default (disabled with `--no-exif-rotation`) - Downscale image before dithering, keeping aspect ratio - Upscale image after dithering, without producing artifacts - Supports input image of types JPEG, GIF (static), PNG, BMP, TIFF - Output to PNG or GIF - Process multiple images with one command - Combine multiple images into an animated GIF - Uses all CPU cores when possible - Support images with transparency (alpha channel is kept the same) ## Installation ### Binary Download a binary from the [releases](https://github.com/makeworld-the-better-one/didder/releases) page. On Unix-based systems you will have to make the file executable with `chmod +x `. You can rename the file to just `didder` for easy access, and move it to `/usr/local/bin/`. On Windows you will have to open a terminal or cmd window in the same directory as the EXE file, or [add it to your PATH](https://stackoverflow.com/a/41895179). Make sure to click "Watch" in the top right, then "Custom" > "Releases" to get notified about new releases! ### Homebrew If you use [Homebrew](https://brew.sh/), you can install didder through the my personal tap. ``` brew tap makew0rld/tap brew install didder ``` You can update it with: ``` brew upgrade didder ``` ### From source **Requirements** - Go 1.14 or later - GNU Make Please note the Makefile does not intend to support Windows, and so there may be issues. ```shell git clone https://github.com/makeworld-the-better-one/didder cd didder # git checkout v1.2.3 # Optionally pin to a specific version instead of the latest commit make # Might be gmake on macOS sudo make install # Install binary and man page ``` macOS users can also use [Homebrew](https://brew.sh/) to install the latest commit of didder: ``` brew tap makew0rld/tap brew install --HEAD didder ``` You can update it with: ``` brew upgrade --fetch-HEAD didder ``` ## Getting started ``` didder [global options] command [command options] [arguments...] ``` The best place to learn about how to use didder is the manual. Run `man didder`, or look at the [MANPAGE.md](./MANPAGE.md) file. If you only read about one flag, read about `--strength`. It's especially important for `bayer` dithering of color images. You can also run `didder` to see the global options and commands. Each command represents a different dithering algorithm, or set of algorithms. You can see the options for each command with `didder help cmd` or `didder cmd --help`. Here's a fully working command as an example: ```shell didder --palette "black white" -i input.jpg -o test.png bayer 16x16 ``` This command dithers `input.jpg` to just use black and white (implicitly converting to grayscale first), using a 16x16 Bayer matrix. The result is written to `test.png`. As another example, here's the command used for the image at the top of the README: ```shell didder -i david.png -o david_dithered.png --palette "black white" --recolor "black F273FF" --upscale 2 bayer 4x4 ``` If you'd like the replicate this yourself, the input image is available [here](https://upload.wikimedia.org/wikipedia/commons/7/71/Michelangelo%27s_David_-_63_grijswaarden.png). ## What method should I use? Generally, using Floyd-Steinberg serpentine dithering will produce results with the fewest artifacts. The command would be: ```shell didder [palette and I/O options] edm --serpentine FloydSteinberg ``` Playing with the strength of the matrix might also be useful. The example above is at full strength, but sometimes that's too noisy. The command for 80% strength looks like this: ```shell didder --strength 80% [palette and I/O options] edm --serpentine FloydSteinberg ``` The main reason for using any other dithering algorithm would be - **Aesthetics** - dithering can be a cool image effect, and different methods will produce different and stronger artifacts - **Speed** - error diffusion dithering is sequential and therefore single-threaded. But ordered dithering, like using `Bayer`, will use all available CPUs, which is much faster. If you want to see examples of the different dithering algorithms, you can look at [this directory](https://github.com/makeworld-the-better-one/dither/tree/master/images/output). Or try them out yourself! ## License This project is licensed under the GPL v3.0. 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[qd;*e짘y+K`Ԫ}wd{ ۱\fO~Rq?{/:a* 2jc[UORv:<~2]V\5}׭EƁ8lqQO +홣ZƱ*뉲; G@N߿̜32\33vzoqyzWOܒ}{㨵mUF E 8LԹ]V'c,_=_D ?i8diy `d3癖dȘ3 Pq2ڴnO C3Oף,=}w2ac][\hWhG}34u< 0e=O5W8՟=2qMqfוk OF )]ݪ0ڱwG}Yy399"Ɣq2iޫݚٿj~Rqq,z*Q=/'}xUa<ƯwckrrX*__ݪ0]ڽҎ:_ #R9EkG_e}8ȾdQ9Be-ڭ λVTdd3 +clR:DAdS=!j_UXCfdu\:d_3˓QqQ(Xe襤BVV@@f8jԚel}z5x q͟gq9#頾l5-L=ym>R_TC@1_an՛Ij}]E}8*{jc~u>x2*ҷNNqo{>_~~&*G?Jsg8{=JRqu>_ݏ<6Vӭ2ݙE/*BGnܶs\u5b׍,lYWqexԟ*sjLxPqvUدa*xޗ~-s=-Td%qΫQ~u;_}lGu}웢 o_gY!wg$\:,*}k<1{|Q8Ⱦ=w3s=#A> L?gG:3Pq}{: 9gJuy}s=8~QkY{|Tdtulz8igOe9kK@U3ͬwckE?߳+ 8~k:E,O{~5(8ٿTdd{}Q]xV]Uޡ {?+K3ִF{ffd3?c,m#^Skd} ;0:~u8}=U,xqdy}s]2~u/N@vHu.r SRq}ǑZ95FQs##ۯ6Χ>R'PclӿǯsI7*3kr~g,sT__M@! Of:Ǝb ; # OPTIONS **-i**, **\--in** *PATH* : Set the input file. This flag can be used multiple times to dither multiple images with the same palette and method. A *PATH* of \'**\-**' stands for standard input. The input file path can also be parsed as a glob. This will only happen if the path contains an asterisk. For example **\-i \'\*.jpg'** will select all the .jpg files in the current directory as input. See this page for more info on glob pattern matching: **-o**, **\--out** *PATH* : Set the output file or directory. A *PATH* of \'**\-**' stands for standard output. If *PATH* is an existing directory, then for each image input, an output file with the same name (but possibly different extension) will be created in that directory. If *PATH* is a file, that ends in .gif (or **\--format gif** is set) then multiple input files will be combined into an animated GIF. **-p**, **\--palette** *COLORS* : Set the color palette used for dithering. Colors are entered as a single quoted argument, with each color separated by a space. Colors can be formatted as RGB tuples (comma separated), hex codes (case-insensitive, with or without the '#'), a single number from 0-255 for grayscale, or a color name from the SVG 1.1 spec (aka the HTML or W3C color names). All colors are interpreted in the sRGB colorspace. A list of all color names is available at Images are converted to grayscale automatically if the palette is grayscale. This produces more correct results. Here's an example of all color formats being used: **\--palette \'23,230,100 D24242 135 forestGreen'** **-r**, **\--recolor** *COLORS* : Set the color palette used for replacing the dithered color palette after dithering. The argument syntax is the same as **\--palette**, with one exception. It also supports RGB*A* tuples, so 4 values. This means you can also choose to change the opacity of a palette color after dithering. The values are not premultiplied, so set the RGB to the color you want as you'd expect. The **\--recolor** flag exists because when palettes that are severely limited in terms of RGB spread are used, accurately representing the image colors with the desired palette is impossible. Instead of accuracy of color, the new goal is accuracy of luminance, or even just accuracy of contrast. For example, the original Nintendo Game Boy used a solely green palette: . By setting **\--palette** to shades of gray and then **\--recolor**-ing to the desired shades of green, input images will be converted to grayscale automatically and then dithered in one dimension (gray), rather than trying to dither a color image (three dimensions, RGB) into a one dimensional green palette. This is similar to "hue shifting" or "colorizing" an image in image editing software. For these situations, **\--recolor** should usually be a palette made up of one hue, and **\--palette** should be the grayscale version of that palette. The **\--palette** could also be just equally spread grayscale values, which would increase the contrast but make the luminance inaccurate. Recoloring can also be useful for increasing contrast on a strange palette, like: **\--palette \'black white' \--recolor \'indigo LimeGreen'**. Setting just **\--palette \'indigo LimeGreen'** would give bad (low contrast) results because that palette is not that far apart in RGB space. These "bad results" are much more pronounced when the input image is in color, because three dimensions are being reduced. **-s**, **\--strength** *DECIMAL/PERCENT* : Set the strength of dithering. This will affect every command except **random**. Decimal format is -1.0 to 1.0, and percentage format is -100% or 100%. The range is not limited. A zero value will be ignored. Defaults to 100%, meaning that the dithering is applied at full strength. Reducing the strength is often visibly similar to reducing contrast. With the **edm** command, **\--strength** can be used to reduce noise, when set to a value around 80%. When using the **bayer** command with a grayscale palette, usually 100% is fine, but for 4x4 matrices or smaller, you may need to reduce the strength. For **bayer** (and by extension **odm**) color palette images, several sites recommend 64% strength (written as 256/4). This is often a good default for **bayer**/**odm** dithering color images, as 100% will distort colors too much. Do not use the default of 100% for Bayer dithering color images. **-j**, **\--threads** *NUM* : Set the number of threads used. By default a thread will be created for each CPU. As dithering is a CPU-bound operation, going above this will not improve performance. This flag does not affect **edm**, as error diffusion dithering cannot be parallelized. **-g**, **\--grayscale** : Make input image(s) grayscale before dithering. **\--saturation** *DECIMAL/PERCENT* : Change input image(s) saturation before dithering. Decimal range is -1.0 to 1.0, percentage range is -100% or 100%. Values that exceed the range will be rounded down. -1.0 or -100% saturation is equivalent to **\--grayscale**. **\--brightness** *DECIMAL/PERCENT* : Change input image(s) saturation before dithering. Decimal range is -1.0 to 1.0, percentage range is -100% or 100%. Values that exceed the range will be rounded down. **\--contrast** *DECIMAL/PERCENT* : Change input image(s) saturation before dithering. Decimal range is -1.0 to 1.0, percentage range is -100% or 100%. Values that exceed the range will be rounded down. **\--no-exif-rotation** : Disable using the EXIF rotation flag in image metadata to rotate the image before processing. **-f**, **\--format** *FORMAT* : Set the output file format. Valid options are \'png' and \'gif'. It will auto detect from filename when possible, so usually this does not need to be set. If **-o** is \'**-**' or a directory, then PNG files will be outputted by default. So this flag can be used to force GIF output instead. If your output file has an extension that is not .png or .gif the format will need to be specified. **\--no-overwrite** : Setting this flag means the program will stop before overwriting an existing file. Any files written before that one was encountered will stay in place. **-c**, **\--compression** *TYPE* : Set the type of PNG compression. Options are \'default', \'no', \'speed', and \'size'. This flag is ignored for non-PNG output. **\--fps** *DECIMAL* : Set frames per second for animated GIF output. Note that not all FPS values can be represented by the GIF format, and so the closest possible one will be chosen. This flag has no default, and is required when animated GIFs are being outputted. This flag is ignored for non animated GIF output. **-l**, **\--loop** *NUM* : Set the number of times animated GIF output should loop. 0 is the default, and will loop infinitely. **-x**, **\--width** *NUM* : Set the width the input image(s) will be resized to, before dithering. Aspect ratio will be maintained if **\--height** is not specified as well. **-y**, **\--height** *NUM* : Set the height the input image(s) will be resized to, before dithering. Aspect ratio will be maintained if **\--width** is not specified as well. **-u**, **\--upscale** *NUM* : Scale image up after dithering. So \'2' will make the output two times as big as the input (after **-x** and/or **-y**). Only integers are allowed, as scaling up by a non-integer amount would distort the dithering pattern and introduce artifacts. **-v**, **\--version** : Get version information. # COMMANDS **random** *MIN MAX* or *RED_MIN RED_MAX GREEN_MIN GREEN_MAX BLUE_MIN BLUE_MAX* : Grayscale and RGB random dithering Accepts two arguments (min and max) for RGB or grayscale, or six (min/max for each channel) to control each RGB channel. Arguments can be separated by commas or spaces. Random dithering adds random noise to the image. The min and max numbers limit the range of the random noise. A good default is -0.5,0.5, which means that a middle gray pixel is 50% likely to become black and 50% likely to become white, assuming a black and white palette. So -0.2,2.0 will reduce the noise (20%), while -0.7,0.7 will increase it (70%). Values like -0.5,0.7 will bias the noise to one end of the channel(s). **-s**, **\--seed** *DECIMAL* : Set the seed for randomization. This will also only use one thread, to keep output deterministic. By default a different seed is chosen each time and multiple threads are used. **bayer** *X* *Y* : Bayer matrix ordered dithering Requires two arguments, for the X and Y dimension of the matrix. They can be separated by a space, comma, or \'x'. Both arguments must be a power of two, with the exception of: 3x5, 5x3, and 3x3. **odm** *NAME/JSON/FILE* : Ordered Dithering Matrix Select or provide an ordered dithering matrix. This only takes one argument, but there a few types available: - A preprogrammed matrix name\ - Inline JSON of a custom matrix\ - Or a path to JSON for your custom matrix. \'**-**' means standard input. Here are all the built-in ordered dithering matrices. You can find details on these matrices here: - ClusteredDot4x4\ - ClusteredDotDiagonal8x8\ - Vertical5x3\ - Horizontal3x5\ - ClusteredDotDiagonal6x6\ - ClusteredDotDiagonal8x8_2\ - ClusteredDotDiagonal16x16\ - ClusteredDot6x6\ - ClusteredDotSpiral5x5\ - ClusteredDotHorizontalLine\ - ClusteredDotVerticalLine\ - ClusteredDot8x8\ - ClusteredDot6x6_2\ - ClusteredDot6x6_3\ - ClusteredDotDiagonal8x8_3 Their names are case-insensitive, and hyphens and underscores are treated the same. The JSON format (whether inline or in a file) looks like the below. The matrix must be "rectangular", meaning each array must have the same length. More information how to use a custom matrix can be found here: ```json { "matrix": [ [12, 5, 6, 13], [4, 0, 1, 7], [11, 3, 2, 8], [15, 10, 9, 14] ], "max": 16 } ``` **edm** *NAME/JSON/FILE* : Error Diffusion Matrix Select or provide an error diffusion matrix. This only takes one argument, but there a few types available: - A preprogrammed matrix name\ - Inline JSON of a custom matrix\ - Or a path to JSON for your custom matrix. \'**-**' means stdin. Here are all the built-in error diffusion matrices. You can find details on these matrices here: - Simple2D\ - FloydSteinberg\ - FalseFloydSteinberg\ - JarvisJudiceNinke\ - Atkinson\ - Stucki\ - Burkes\ - Sierra (or Sierra3)\ - TwoRowSierra (or Sierra2)\ - SierraLite (or Sierra2_4A)\ - StevenPigeon Their names are case-insensitive, and hyphens and underscores are treated the same. The JSON format (whether inline or in a file) for a custom matrix is very simple, just a 2D array. The matrix must be "rectangular", meaning each array must have the same length. **-s**, **\--serpentine** : Enable serpentine dithering, which "snakes" back and forth when moving down the image, instead of going left-to-right each time. This can reduce artifacts or patterns in the noise. # TIPS Read about **\--strength** if you haven't already. Read about **\--recolor** if you haven't already. It's easy to mess up a dithered image by scaling it manually. It's best to scale the image to the size you want before dithering (externally, or with **\--width** and/or **\--height**), and then leave it. If you need to scale it up afterward, use **\--upscale**, rather than another tool. This will prevent image artifacts and blurring. Be wary of environments where you can't make sure an image will be displayed at 100% size, pixel for pixel. Make sure to at least use nearest-neighbor scaling, do your best to preserve sharp pixel edges. Dithered images must only be encoded in a lossless image format. This is why the tool only outputs PNG and GIF. To increase the dithering artifacts for aesthetic effect, you can downscale the image before dithering and upscale after. Like if the image is 1000 pixels tall, your command can look like **didder --height 500 --upscale 2 [...]**. Depending on the input image size and what final size you want, you can of course just upscale as well. If your palette (original or recolor) is low-spread — meaning it doesn't span much of the available shades of a single hue or the entire RGB space — you can use flags like **\--brightness**, **\--contrast**, and **\--saturation** to improve the way dithered images turn out. For example, if your palette is dark, you can turn up the brightness. As mentioned above, these flags apply their transformations to the original image and will not adjust your selected palette colors. # EXAMPLES **didder \--palette \"black white" -i input.jpg -o test.png bayer 16x16** : This command dithers `input.jpg` using only black and white (implicitly converting the image to grayscale first), using a 16x16 Bayer matrix. The result is written to `test.png`. **didder \--palette \"black white" -i input.jpg -o test.png odm ClusteredDot4x4** : Same command as above, but dithering with the preprogrammed ordered dithering matrix called ClusteredDot4x4. **didder -i david.png -o david_dithered.png \--palette \"black white" \--recolor \"black F273FF" \--upscale 2 bayer 4x4** : This is the command used for the README. It dithers using a 4x4 Bayer matrix, initially to black and white, which is then recolored to black and purple. Dithering to black and purple directly would produce much lower contrast results. The dithered image is upscaled to be two times larger, so that the Bayer dithering artifacts can be seen more clearly. **didder -i input.png -o output.png -p \"1E1E1E CDCDCD EDEDED FFFFFF" -r \"11161e 116bcd 63b3ed e1efff" \--strength 64% \--brightness 20% bayer 32x32** : This command uses a blue recolor palette, one that is biased to being darker. The palette can be viewed at . The dithering palette is the grayscale version of those colors, to keep luminance accurate. Strength is set to 64%, which although usually recommended for Bayer dithering of color images, works well here. Alternatively, one could try and increase **\--contrast**. Finally, the brightness is increased to compensate for the dark palette. **didder -p \"black white" \--recolor \"darkgreen white" -i frame_01.png -i frame_02.png -o output.gif \--fps 1 random -0.5,0.5** : This command takes two input images and creates an animated GIF, dithering and recoloring them along the way. The GIF moves at 1 frame per second, and by default loops infinitely. Random dithering is used, with recommended default of -0.5,0.5. # REPORTING BUGS Any bugs can be reported by creating an issue on GitHub: didder-1.3.0/fake_quantizer.go000066400000000000000000000012231476364616000163200ustar00rootroot00000000000000package main import ( "image" "image/color" ) // Like in the dither library, see // https://github.com/makeworld-the-better-one/dither/blob/3714c39500bc23a87a4fa14053344f201cc5beff/draw.go#L128-L156 // Use for specifying the recolor palette for GIF encoding // fakeQuantizer implements draw.Quantizer. It ignores the provided image // and just returns the provided palette each time. This is useful for places that // only allow you to set the palette through a draw.Quantizer, like the image/gif // package. type fakeQuantizer struct { p []color.Color } func (fq *fakeQuantizer) Quantize(p color.Palette, m image.Image) color.Palette { return fq.p } didder-1.3.0/go.mod000066400000000000000000000004001476364616000140630ustar00rootroot00000000000000module github.com/makeworld-the-better-one/didder go 1.16 require ( github.com/disintegration/imaging v1.6.2 github.com/makeworld-the-better-one/dither/v2 v2.4.0 github.com/urfave/cli/v2 v2.3.0 golang.org/x/image v0.0.0-20210220032944-ac19c3e999fb ) didder-1.3.0/go.sum000066400000000000000000000051671476364616000141270ustar00rootroot00000000000000github.com/BurntSushi/toml v0.3.1/go.mod h1:xHWCNGjB5oqiDr8zfno3MHue2Ht5sIBksp03qcyfWMU= github.com/cpuguy83/go-md2man/v2 v2.0.0-20190314233015-f79a8a8ca69d h1:U+s90UTSYgptZMwQh2aRr3LuazLJIa+Pg3Kc1ylSYVY= github.com/cpuguy83/go-md2man/v2 v2.0.0-20190314233015-f79a8a8ca69d/go.mod h1:maD7wRr/U5Z6m/iR4s+kqSMx2CaBsrgA7czyZG/E6dU= github.com/davecgh/go-spew v1.1.0 h1:ZDRjVQ15GmhC3fiQ8ni8+OwkZQO4DARzQgrnXU1Liz8= github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38= github.com/disintegration/imaging v1.6.2 h1:w1LecBlG2Lnp8B3jk5zSuNqd7b4DXhcjwek1ei82L+c= github.com/disintegration/imaging v1.6.2/go.mod h1:44/5580QXChDfwIclfc/PCwrr44amcmDAg8hxG0Ewe4= github.com/makeworld-the-better-one/dither/v2 v2.4.0 h1:Az/dYXiTcwcRSe59Hzw4RI1rSnAZns+1msaCXetrMFE= github.com/makeworld-the-better-one/dither/v2 v2.4.0/go.mod h1:VBtN8DXO7SNtyGmLiGA7IsFeKrBkQPze1/iAeM95arc= github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM= github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4= github.com/russross/blackfriday/v2 v2.0.1 h1:lPqVAte+HuHNfhJ/0LC98ESWRz8afy9tM/0RK8m9o+Q= github.com/russross/blackfriday/v2 v2.0.1/go.mod h1:+Rmxgy9KzJVeS9/2gXHxylqXiyQDYRxCVz55jmeOWTM= github.com/shurcooL/sanitized_anchor_name v1.0.0 h1:PdmoCO6wvbs+7yrJyMORt4/BmY5IYyJwS/kOiWx8mHo= github.com/shurcooL/sanitized_anchor_name v1.0.0/go.mod h1:1NzhyTcUVG4SuEtjjoZeVRXNmyL/1OwPU0+IJeTBvfc= github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME= github.com/stretchr/testify v1.6.1 h1:hDPOHmpOpP40lSULcqw7IrRb/u7w6RpDC9399XyoNd0= github.com/stretchr/testify v1.6.1/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg= github.com/urfave/cli/v2 v2.3.0 h1:qph92Y649prgesehzOrQjdWyxFOp/QVM+6imKHad91M= github.com/urfave/cli/v2 v2.3.0/go.mod h1:LJmUH05zAU44vOAcrfzZQKsZbVcdbOG8rtL3/XcUArI= golang.org/x/image v0.0.0-20191009234506-e7c1f5e7dbb8/go.mod h1:FeLwcggjj3mMvU+oOTbSwawSJRM1uh48EjtB4UJZlP0= golang.org/x/image v0.0.0-20210220032944-ac19c3e999fb h1:fqpd0EBDzlHRCjiphRR5Zo/RSWWQlWv34418dnEixWk= golang.org/x/image v0.0.0-20210220032944-ac19c3e999fb/go.mod h1:FeLwcggjj3mMvU+oOTbSwawSJRM1uh48EjtB4UJZlP0= golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ= gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0= gopkg.in/yaml.v2 v2.2.3/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI= gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c h1:dUUwHk2QECo/6vqA44rthZ8ie2QXMNeKRTHCNY2nXvo= gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM= didder-1.3.0/main.go000066400000000000000000000103421476364616000142360ustar00rootroot00000000000000package main import ( "errors" "fmt" "os" "github.com/urfave/cli/v2" ) // Set by compiler, see Makefile var ( version = "v1.3.0" commit = "unknown" builtBy = "unknown" ) func main() { app := &cli.App{ Name: "didder", Usage: "dither images with a variety of algorithms and processing options.", Description: "didder dithers images.\n\nRun `man didder` for more information, or view the manual online:\nhttps://github.com/makeworld-the-better-one/didder/blob/main/MANPAGE.md", UseShortOptionHandling: true, Flags: []cli.Flag{ &cli.StringFlag{ Name: "strength", Aliases: []string{"s"}, }, &cli.UintFlag{ Name: "threads", Aliases: []string{"j"}, }, &cli.StringFlag{ Name: "palette", Aliases: []string{"p"}, Required: true, }, &cli.BoolFlag{ Name: "grayscale", Aliases: []string{"g"}, }, &cli.StringFlag{ Name: "saturation", }, &cli.StringFlag{ Name: "brightness", }, &cli.StringFlag{ Name: "contrast", }, &cli.StringFlag{ Name: "recolor", Aliases: []string{"r"}, }, &cli.BoolFlag{ Name: "no-exif-rotation", }, &cli.StringFlag{ Name: "format", Aliases: []string{"f"}, Value: "png", }, &cli.StringFlag{ Name: "out", Aliases: []string{"o"}, Required: true, }, &cli.StringSliceFlag{ Name: "in", Aliases: []string{"i"}, Required: true, }, &cli.BoolFlag{ Name: "no-overwrite", }, &cli.StringFlag{ Name: "compression", Aliases: []string{"c"}, Value: "default", }, &cli.Float64Flag{ Name: "fps", }, &cli.UintFlag{ Name: "loop", Aliases: []string{"l"}, }, &cli.UintFlag{ Name: "width", Aliases: []string{"x"}, }, &cli.UintFlag{ Name: "height", Aliases: []string{"y"}, }, &cli.UintFlag{ Name: "upscale", Aliases: []string{"u"}, Value: 1, }, &cli.BoolFlag{ Name: "version", Aliases: []string{"v"}, }, }, Commands: []*cli.Command{ { Name: "random", Usage: "grayscale and RGB random dithering", Flags: []cli.Flag{ &cli.Int64Flag{ Name: "seed", Aliases: []string{"s"}, }, }, UseShortOptionHandling: true, Action: random, SkipFlagParsing: true, // Allow for numbers that start with a negative }, { Name: "bayer", Usage: "Bayer matrix ordered dithering", UseShortOptionHandling: true, Action: bayer, }, { Name: "odm", Usage: "Ordered Dither Matrix", UseShortOptionHandling: true, Action: odm, }, { Name: "edm", Usage: "Error Diffusion Matrix", Flags: []cli.Flag{ &cli.BoolFlag{ Name: "serpentine", Aliases: []string{"s"}, }, }, UseShortOptionHandling: true, Action: edm, }, }, Before: preProcess, Action: func(c *cli.Context) error { return errors.New("no command specified") }, } // Handle version flag if len(os.Args) == 2 && (os.Args[1] == "-v" || os.Args[1] == "--version") { fmt.Println("didder", version) fmt.Println("Commit:", commit) fmt.Println("Built by:", builtBy) return } // Hack around issue where required flags are still required even for help // https://github.com/urfave/cli/issues/1247 if len(os.Args) == 3 { if os.Args[1] == "h" || os.Args[1] == "help" { // Like: didder help bayer for _, c := range app.Commands { if c.Name == os.Args[2] { cli.HelpPrinter(os.Stdout, cli.CommandHelpTemplate, c) return } } fmt.Println("no command with that name") os.Exit(1) } else if os.Args[len(os.Args)-1] == "-h" || os.Args[len(os.Args)-1] == "--help" { // Like: didder bayer --help for _, c := range app.Commands { if c.Name == os.Args[1] { cli.HelpPrinter(os.Stdout, cli.CommandHelpTemplate, c) return } } fmt.Println("no command with that name") os.Exit(1) } } err := app.Run(os.Args) if err != nil { if len(os.Args) == 1 { // Just ran the command with no flags return } fmt.Println(err) os.Exit(1) } } didder-1.3.0/subcommand_helpers.go000066400000000000000000000344701476364616000171740ustar00rootroot00000000000000package main import ( "errors" "fmt" "image" "image/color" "image/draw" "image/gif" "image/png" "io" "math" "os" "path/filepath" "strconv" "strings" "github.com/disintegration/imaging" "github.com/makeworld-the-better-one/dither/v2" "github.com/urfave/cli/v2" "golang.org/x/image/colornames" ) // parsePercentArg takes a string like "0.5" or "50%" and will return a float // like 50 or 0.5, depending on the second argument. An empty string returns 0. // // If `maxOne` is true, then "50%" will return 0.5. Otherwise it will return 50. func parsePercentArg(arg string, maxOne bool) (float64, error) { if arg == "" { return 0, nil } if strings.HasSuffix(arg, "%") { arg = arg[:len(arg)-1] f64, err := strconv.ParseFloat(arg, 64) if err != nil { return 0, err } if maxOne { f64 /= 100.0 } return f64, nil } f64, err := strconv.ParseFloat(arg, 64) if !maxOne { f64 *= 100.0 } return f64, err } // globalFlag returns the value of flag at the top level of the command. // For example, with the command: // dither --threads 1 edm -s Simple2D // "threads" is a global flag, and "s" is a flag local to the edm subcommand. func globalFlag(flag string, c *cli.Context) interface{} { ancestor := c.Lineage()[len(c.Lineage())-1] if len(ancestor.Args().Slice()) == 0 { // When the global context calls this func, the last in the lineage // has no args for some reason. So return the second-last instead. return c.Lineage()[len(c.Lineage())-2].Value(flag) } return ancestor.Value(flag) } // globalIsSet returns a bool indicating whether the provided global flag // was actually set. func globalIsSet(flag string, c *cli.Context) bool { ancestor := c.Lineage()[len(c.Lineage())-1] if len(ancestor.Args().Slice()) == 0 { // See globalFlag for why this if statement exists return c.Lineage()[len(c.Lineage())-2].IsSet(flag) } return ancestor.IsSet(flag) } // parseArgs takes arguments and splits them using the provided split characters. func parseArgs(args []string, splitRunes string) []string { finalArgs := make([]string, 0) for _, arg := range args { finalArgs = append(finalArgs, strings.FieldsFunc(arg, func(c rune) bool { for _, c2 := range splitRunes { if c == c2 { return true } } return false })...) } return finalArgs } func hexToColor(hex string) (color.NRGBA, error) { // Modified from https://github.com/lucasb-eyer/go-colorful/blob/v1.2.0/colors.go#L333 hex = strings.TrimPrefix(hex, "#") format := "%02x%02x%02x" var r, g, b uint8 n, err := fmt.Sscanf(strings.ToLower(hex), format, &r, &g, &b) if err != nil { return color.NRGBA{}, err } if n != 3 { return color.NRGBA{}, fmt.Errorf("%s is not a hex color", hex) } return color.NRGBA{r, g, b, 255}, nil } func rgbToColor(s string) (color.NRGBA, error) { format := "%d,%d,%d" var r, g, b uint8 n, err := fmt.Sscanf(s, format, &r, &g, &b) if err != nil { return color.NRGBA{}, err } if n != 3 { return color.NRGBA{}, fmt.Errorf("%s is not an RGB tuple", s) } return color.NRGBA{r, g, b, 255}, nil } func rgbaToColor(s string) (color.NRGBA, error) { format := "%d,%d,%d,%d" var r, g, b, a uint8 n, err := fmt.Sscanf(s, format, &r, &g, &b, &a) if err != nil { return color.NRGBA{}, err } if n != 4 { return color.NRGBA{}, fmt.Errorf("%s is not an RGBA tuple", s) } // Parse as non-premult, as that's more user-friendly return color.NRGBA{r, g, b, a}, nil } // parseColors takes args and turns them into a color slice. All returned // colors are guaranteed to only be color.NRGBA. func parseColors(flag string, c *cli.Context) ([]color.Color, error) { args := parseArgs([]string{globalFlag(flag, c).(string)}, " ") colors := make([]color.Color, len(args)) for i, arg := range args { // Try to parse as RGB numbers, then hex, then grayscale, then SVG colors, then fail // Optionally try for RGBA if it's recolor, see #1 if strings.Count(arg, ",") == 2 { rgbColor, err := rgbToColor(arg) if err != nil { return nil, fmt.Errorf("%s: %s is not a valid RGB tuple. Example: 25,200,150", flag, arg) } colors[i] = rgbColor continue } if flag == "recolor" && strings.Count(arg, ",") == 3 { rgbaColor, err := rgbaToColor(arg) if err != nil { return nil, fmt.Errorf("%s: %s is not a valid RGBA tuple. Example: 25,200,150,100", flag, arg) } colors[i] = rgbaColor continue } hexColor, err := hexToColor(arg) if err == nil { colors[i] = hexColor continue } n, err := strconv.Atoi(arg) if err == nil { if n > 255 || n < 0 { return nil, fmt.Errorf("%s: single numbers like %d must be in the range 0-255", flag, n) } colors[i] = color.NRGBA{uint8(n), uint8(n), uint8(n), 255} continue } htmlColor, ok := colornames.Map[strings.ToLower(arg)] if ok { colors[i] = color.NRGBAModel.Convert(htmlColor).(color.NRGBA) continue } return nil, fmt.Errorf("%s: %s not recognized as an RGB tuple, hex code, number 0-255, or SVG color name", flag, arg) } return colors, nil } // getInputImage takes an input image arg and returns an image that has // modifications applied. func getInputImage(arg string, c *cli.Context) (image.Image, error) { var img image.Image var err error if arg == "-" { img, err = imaging.Decode(os.Stdin, autoOrientation) } else { img, err = imaging.Open(arg, autoOrientation) } if err != nil { return nil, err } if width != 0 || height != 0 { // Box sampling is quick and fast, and better then others at downscaling // Downscaling will be a much more common use case for pre-dither scaling // then upscaling // https://pkg.go.dev/github.com/disintegration/imaging#ResampleFilter // https://en.wikipedia.org/wiki/Image_scaling#Box_sampling img = imaging.Resize(img, width, height, imaging.Box) } if grayscale { img = imaging.Grayscale(img) } if saturation != 0 { img = imaging.AdjustSaturation(img, saturation) } if contrast != 0 { img = imaging.AdjustContrast(img, contrast) } if brightness != 0 { img = imaging.AdjustBrightness(img, brightness) } return img, nil } // From dither library func copyImage(dst draw.Image, src image.Image) { draw.Draw(dst, src.Bounds(), src, src.Bounds().Min, draw.Src) } func copyOfImage(img image.Image) *image.RGBA { dst := image.NewRGBA(img.Bounds()) copyImage(dst, img) return dst } /////// // recolor will recolor the image pixels if necessary. It should be called // before writing any image. It should only be given a dithered image. // It will copy an image if it cannot draw on it. // // If the input image is *image.Paletted, the output will always be of that type too. func recolor(src image.Image) image.Image { if len(recolorPalette) == 0 { return src } // Modified and returned value var img draw.Image // getRecolor takes an image color and returns the recolor one getRecolor := func(a color.Color) color.Color { // palette and recolorPalette are both NRGBA, so use that here too c := color.NRGBAModel.Convert(a).(color.NRGBA) for i := range palette { pc := palette[i].(color.NRGBA) if pc.R == c.R && pc.G == c.G && pc.B == c.B { // Colors match. Alpha is ignored because palette colors aren't // allowed alpha, so theirs will always be 255. While the image // might have a different alpha at that point return recolorPalette[i] } } // This should never happen return recolorPalette[0] } // Fast path for paletted images if p, ok := src.(*image.Paletted); ok { // For each color in the image palette, replace it with the equivalent // recolor palette color for i, c := range p.Palette { p.Palette[i] = getRecolor(c) } return p } var ok bool if img, ok = src.(draw.Image); !ok { // Can't be changed // Instead make a copy and recolor and return that img = copyOfImage(src) } // Swap each image pixel b := img.Bounds() for y := b.Min.Y; y < b.Max.Y; y++ { for x := b.Min.X; x < b.Max.X; x++ { // Image pixel -> convert to RGBA -> find recolor palette color using map // -> set color img.Set(x, y, getRecolor(img.At(x, y))) } } return img } // postProcImage post-processes the image, applying recolor and upscaling. // // If the input image is *image.Paletted, the output will always be of that type too. func postProcImage(img image.Image) image.Image { img = recolor(img) if upscale == 1 { return img } var palette color.Palette if p, ok := img.(*image.Paletted); ok { palette = p.Palette } img = imaging.Resize( img, img.Bounds().Dx()*upscale, 0, imaging.NearestNeighbor, ) if len(palette) == 0 { return img } pi := image.NewPaletted(img.Bounds(), palette) copyImage(pi, img) return pi } // processImages dithers all the input images and writes them. // It handles all image I/O. func processImages(d *dither.Ditherer, c *cli.Context) error { outPath := globalFlag("out", c).(string) // Setup for if it's an animated GIF output // Overall adapted from: // https://github.com/makeworld-the-better-one/dither/blob/v2.0.0/examples/gif_animation.go isAnimGIF := len(inputImages) > 1 && outFormat == "gif" && !outIsDir var frames []*image.Paletted if isAnimGIF { frames = make([]*image.Paletted, len(inputImages)) } var delays []int var animGIF gif.GIF if isAnimGIF { if !globalIsSet("fps", c) { return errors.New("output will be animated GIF, but --fps flag is not set") } delays = make([]int, len(inputImages)) for i := range delays { // Round to the nearest possible frame rate supported by the GIF format // See for details: https://superuser.com/a/1449370 // A rolling average is not done because it's harder to code and looks // bad: https://superuser.com/q/1459724 // // Lowest allowed delay is 1, or 100 FPS. delays[i] = int(math.Max(math.Round(100.0/globalFlag("fps", c).(float64)), 1)) } loopCount := int(globalFlag("loop", c).(uint)) if loopCount == 1 { // Looping once is set using -1 in the image/gif library loopCount = -1 } else if loopCount != 0 { // The CLI flag is equal to the number of times looped // But for gif.GIF.LoopCount, "the animation is looped LoopCount+1 times." loopCount -= 1 } animGIF = gif.GIF{ Image: frames, Delay: delays, LoopCount: loopCount, } } // Go through images and dither (and write if not an animated GIF) for i, inputPath := range inputImages { img, err := getInputImage(inputPath, c) if err != nil { return fmt.Errorf("error loading '%s': %w", inputPath, err) } if isAnimGIF { if i == 0 { // Use the config of the first image for the animated GIF var config image.Config frames[0], config = d.DitherPalettedConfig(img) frames[0] = postProcImage(frames[0]).(*image.Paletted) if len(recolorPalette) == 0 { animGIF.Config = config } else { // Same config as the Ditherer would give, but with the recolor palette animGIF.Config = image.Config{ ColorModel: color.Palette(recolorPalette), Width: frames[0].Bounds().Dx(), Height: frames[0].Bounds().Dy(), } } continue } // Later frames if upscale == 1 && !img.Bounds().Eq(frames[0].Bounds()) { // Upscale check is needed because otherwise frames[0] will be upscaled and not match return fmt.Errorf( "image '%s' isn't the same size as '%s', all sizes must match to create an animated GIF", inputPath, inputImages[0], ) } frames[i] = d.DitherPaletted(img) frames[i] = postProcImage(frames[i]).(*image.Paletted) // Do bounds check now, if it didn't happen before because of upscaling if upscale != 1 && !frames[i].Bounds().Eq(frames[0].Bounds()) { return fmt.Errorf( "image '%s' isn't the same size as '%s', all sizes must match to create an animated GIF", inputPath, inputImages[0], ) } continue } // Not an animated GIF // Write out the image now // (partially copied below, outside the loop) var file io.WriteCloser var path string if outPath == "-" { file = os.Stdout path = "stdout" } else { if outIsDir { // Inside output directory // Same name as input file but potentially different extension path = filepath.Join( outPath, strings.TrimSuffix(filepath.Base(inputPath), filepath.Ext(inputPath))+"."+outFormat, ) } else { // Output file path path = outPath } file, err = os.OpenFile(path, outFileFlags, 0644) if err != nil { return fmt.Errorf("'%s': %w", path, err) } } if outFormat == "png" { img = postProcImage(d.Dither(img)) err = (&png.Encoder{CompressionLevel: compLevel}).Encode(file, img) if err != nil { defer file.Close() // Keep (possibly stdout) open to write error messages then close return fmt.Errorf("error writing PNG to '%s': %w", path, err) } file.Close() } else { // Output static GIF // Adapted from: // https://github.com/makeworld-the-better-one/dither/blob/v2.0.0/examples/gif_image.go if !postProcNeeded { // No post // GIF encoder calls the ditherer err = gif.Encode( file, img, &gif.Options{ NumColors: len(palette), Quantizer: d, Drawer: d, }, ) } else { // Dither and post-process first, and use recolor palette if needed // The gif package will not change the image if it's *image.Paletted // So even though Drawer is not set to the ditherer it'll be fine, // and the default FloydSteinberg Drawer won't be used img = postProcImage(d.DitherPaletted(img)) var quantizer draw.Quantizer if len(recolorPalette) == 0 { quantizer = d } else { quantizer = &fakeQuantizer{recolorPalette} } err = gif.Encode( file, img, &gif.Options{ NumColors: len(recolorPalette), Quantizer: quantizer, }, ) } if err != nil { defer file.Close() return fmt.Errorf("error writing GIF to '%s': %w", path, err) } file.Close() } } // Either all images have been written and everything is done, or the animated GIF // needs to be saved. if !isAnimGIF { return nil } // Partially copied from above var file io.WriteCloser var path string var err error if outPath == "-" { file = os.Stdout path = "stdout" } else { // Output file path path = outPath file, err = os.OpenFile(path, outFileFlags, 0644) if err != nil { return fmt.Errorf("'%s': %w", path, err) } } err = gif.EncodeAll(file, &animGIF) if err != nil { defer file.Close() return fmt.Errorf("error writing GIF to '%s': %w", path, err) } file.Close() return nil } didder-1.3.0/subcommands.go000066400000000000000000000310241476364616000156250ustar00rootroot00000000000000package main import ( "encoding/json" "errors" "fmt" "image/color" "image/png" "io/ioutil" "math/rand" "os" "path/filepath" "runtime" "strconv" "strings" "time" "github.com/disintegration/imaging" "github.com/makeworld-the-better-one/dither/v2" "github.com/urfave/cli/v2" ) const ( unsupportedFormat string = "'%s' is an unsupported format, only 'png' or 'gif' are accepted" ) var ( // palette stores the palette colors. It's set after pre-processing. // Guaranteed to only hold color.NRGBA. palette []color.Color // recolorPalette stores the recolor palette colors. It's set after pre-processing. // Guaranteed to only hold color.NRGBA. recolorPalette []color.Color grayscale bool // Range -100,100 saturation float64 brightness float64 contrast float64 autoOrientation imaging.DecodeOption inputImages []string outFormat string // "png" or "gif" outIsDir bool compLevel png.CompressionLevel outFileFlags int // For os.OpenFile width int height int // upscale will always be 1 or above upscale int ditherer *dither.Ditherer // range [-1, 1] strength float32 // Is post-processing needed? postProcNeeded bool ) // preProcess is automatically called by the app before anything else. // It's run in the global context. func preProcess(c *cli.Context) error { runtime.GOMAXPROCS(int(c.Uint("threads"))) var err error palette, err = parseColors("palette", c) if err != nil { return err } if len(palette) < 2 { return errors.New("the palette must have at least two colors") } if c.String("recolor") != "" { recolorPalette, err = parseColors("recolor", c) if err != nil { return err } if len(recolorPalette) != len(palette) { return errors.New("recolor palette must have the same number of colors as the initial palette") } } // Check if palette is grayscale and make image grayscale // Or if the user forces it grayscale = true if !c.Bool("grayscale") { // Grayscale isn't specified by the user // So check to see if palette is grayscale for _, c := range palette { r, g, b, _ := c.RGBA() if r != g || g != b { grayscale = false break } } } saturation, err = parsePercentArg(c.String("saturation"), false) if err != nil { return fmt.Errorf("saturation: %w", err) } if saturation <= -100 { grayscale = true saturation = 0 } brightness, err = parsePercentArg(c.String("brightness"), false) if err != nil { return fmt.Errorf("brightness: %w", err) } contrast, err = parsePercentArg(c.String("contrast"), false) if err != nil { return fmt.Errorf("contrast: %w", err) } autoOrientation = imaging.AutoOrientation(!c.Bool("no-exif-rotation")) inputImages = make([]string, 0) for _, path := range c.StringSlice("in") { if strings.Contains(path, "*") { // Parse as glob paths, err := filepath.Glob(path) if err != nil { return fmt.Errorf("bad glob pattern '%s': %w", path, err) } inputImages = append(inputImages, paths...) } else { inputImages = append(inputImages, path) } } formatVal := c.String("format") if formatVal != "png" && formatVal != "gif" { return fmt.Errorf(unsupportedFormat, formatVal) } // Figure out output format outVal := c.String("out") if outVal == "-" { // Outputting to stdout, so just use whatever the flag is outFormat = formatVal } else { // Outputting to dir or file outFI, err := os.Stat(outVal) if err == nil && outFI.IsDir() { // Exists and is a directory // Just use what the flag is outFormat = formatVal outIsDir = true } else { // Outputting to file, that already exists // Or something that doesn't exist - assumed to be a file if !c.IsSet("format") { // Format wasn't set, so ignore default value of "png" // Try to figure out format from output filename ext := strings.TrimPrefix(filepath.Ext(outVal), ".") if ext == "png" || ext == "gif" { // Acceptable extension outFormat = ext } else if ext == "" { // No extension, use default format outFormat = "png" } else { // Unsupported extension and no format flag override return fmt.Errorf(unsupportedFormat, ext) } } else { // Format flag was set, so ignore what the file looks like outFormat = formatVal } } } // Multiple input images are only valid if the output is GIF, // or if the output points to a directory. if len(inputImages) > 1 && (outFormat != "gif" && !outIsDir) { return fmt.Errorf("multiple input images are only allowed if the output format is GIF, or an existing directory") } if outFormat == "gif" && len(palette) > 256 { return errors.New("the GIF format only supports 256 colors or less in the palette") } // Set PNG compression type switch c.String("compression") { case "default": compLevel = png.DefaultCompression case "no": compLevel = png.NoCompression case "speed": compLevel = png.BestSpeed case "size": compLevel = png.BestCompression default: return fmt.Errorf("invalid compression type '%s'", c.String("compression")) } if c.Bool("no-overwrite") { outFileFlags = os.O_WRONLY | os.O_CREATE | os.O_EXCL } else { outFileFlags = os.O_WRONLY | os.O_CREATE | os.O_TRUNC } // Set here for convenience width = int(c.Uint("width")) height = int(c.Uint("height")) upscale = int(c.Uint("upscale")) if upscale == 0 { // Invalid upscale = 1 } ditherer = dither.NewDitherer(palette) tmp, err := parsePercentArg(c.String("strength"), true) if err != nil { return fmt.Errorf("strength: %w", err) } strength = float32(tmp) if strength == 0 { // Ignore strength = 1 } if len(recolorPalette) != 0 || upscale > 1 { postProcNeeded = true } return nil } func random(c *cli.Context) error { args := parseArgs(c.Args().Slice(), " ,") // Manually parse out --seed, -s flag // The manual parsing is done to allow for numbers that start with a negative // which would otherwise be interpreted as flags seedIsSet := false var seed int64 if len(args) >= 1 { if args[0] == "--seed" || args[0] == "-s" { if len(args) >= 2 { // Parse and set seed value var err error seed, err = strconv.ParseInt(args[1], 10, 64) if err != nil { return fmt.Errorf("couldn't parse seed value: %w", err) } seedIsSet = true args = args[2:] } else { // Seed flag but no value after it return errors.New("no value after seed flag") } } else if args[0] == "--help" || args[0] == "-h" { // Display the help return cli.ShowCommandHelp(c, "random") } } if len(args) != 2 && len(args) != 6 { return errors.New("random needs 2 or 6 arguments") } floatArgs := make([]float32, len(args)) for i, arg := range args { f64, err := parsePercentArg(arg, true) if err != nil { return err } floatArgs[i] = float32(f64) } if seedIsSet { rand.Seed(seed) } else { // Seed with something that won't repeat next use rand.Seed(time.Now().UnixNano()) } if len(floatArgs) == 2 { if grayscale { ditherer.Mapper = dither.RandomNoiseGrayscale(floatArgs[0], floatArgs[1]) } else { // Use the two arguments for all channels ditherer.Mapper = dither.RandomNoiseRGB(floatArgs[0], floatArgs[1], floatArgs[0], floatArgs[1], floatArgs[0], floatArgs[1]) } } else { ditherer.Mapper = dither.RandomNoiseRGB(floatArgs[0], floatArgs[1], floatArgs[2], floatArgs[3], floatArgs[4], floatArgs[5]) } if seedIsSet { // Make deterministic ditherer.SingleThreaded = true } err := processImages(ditherer, c) if err != nil { return err } return nil } func bayer(c *cli.Context) error { args := parseArgs(c.Args().Slice(), " ,x") if len(args) != 2 { return errors.New("bayer needs 2 arguments exactly. Example: 4x4") } uintArgs := make([]uint, 2) for i, arg := range args { u64, err := strconv.ParseUint(arg, 10, 0) if err != nil { return err } uintArgs[i] = uint(u64) } // Validate args to prevent dither.Bayer from panicking x, y := uintArgs[0], uintArgs[1] if x == 0 || y == 0 { return errors.New("neither dimension can be 0") } if x == 1 && y == 1 { return errors.New("a 1x1 matrix will not dither the image") } if ((x&(x-1)) != 0 || (y&(y-1)) != 0) && // Power of two? !((x == 3 && y == 3) || (x == 5 && y == 3) || (x == 3 && y == 5)) { // Exceptions // Not a power of two, and not an exception return errors.New("both dimensions must be powers of two") } ditherer.Mapper = dither.Bayer(x, y, strength) err := processImages(ditherer, c) if err != nil { return err } return nil } var odmName = map[string]dither.OrderedDitherMatrix{ "clustereddot4x4": dither.ClusteredDot4x4, "clustereddotdiagonal8x8": dither.ClusteredDotDiagonal8x8, "vertical5x3": dither.Vertical5x3, "horizontal3x5": dither.Horizontal3x5, "clustereddotdiagonal6x6": dither.ClusteredDotDiagonal6x6, "clustereddotdiagonal8x8_2": dither.ClusteredDotDiagonal8x8_2, "clustereddotdiagonal16x16": dither.ClusteredDotDiagonal16x16, "clustereddot6x6": dither.ClusteredDot6x6, "clustereddotspiral5x5": dither.ClusteredDotSpiral5x5, "clustereddothorizontalline": dither.ClusteredDotHorizontalLine, "clustereddotverticalline": dither.ClusteredDotVerticalLine, "clustereddot8x8": dither.ClusteredDot8x8, "clustereddot6x6_2": dither.ClusteredDot6x6_2, "clustereddot6x6_3": dither.ClusteredDot6x6_3, "clustereddotdiagonal8x8_3": dither.ClusteredDotDiagonal8x8_3, } func odm(c *cli.Context) error { args := c.Args().Slice() if len(args) != 1 { return errors.New("odm only accepts one argument") } var matrix dither.OrderedDitherMatrix matrix, ok := odmName[strings.ReplaceAll(strings.ToLower(args[0]), "-", "_")] if !ok { // Either inline JSON, path to file, or an error err := json.Unmarshal([]byte(args[0]), &matrix) if err != nil { bytes, err := ioutil.ReadFile(args[0]) if err != nil { return errors.New("couldn't process argument as matrix name, inline JSON, or path to accessible JSON file") } err = json.Unmarshal(bytes, &matrix) if err != nil { return errors.New("couldn't process argument as matrix name, inline JSON, or path to accessible JSON file") } } // Validate matrix if matrix.Max == 0 { return errors.New("the max value of the matrix cannot be 0") } if len(matrix.Matrix) == 0 { return errors.New("matrix is empty") } // Is it rectangular? width := len(matrix.Matrix[0]) if width == 0 { return errors.New("matrix has empty row") } for _, row := range matrix.Matrix { if len(row) != width { return errors.New("matrix is not rectangular, all rows must be the same length") } } } ditherer.Mapper = dither.PixelMapperFromMatrix(matrix, strength) err := processImages(ditherer, c) if err != nil { return err } return nil } var edmName = map[string]dither.ErrorDiffusionMatrix{ "simple2d": dither.Simple2D, "floydsteinberg": dither.FloydSteinberg, "falsefloydsteinberg": dither.FalseFloydSteinberg, "jarvisjudiceninke": dither.JarvisJudiceNinke, "atkinson": dither.Atkinson, "stucki": dither.Stucki, "burkes": dither.Burkes, "sierra": dither.Sierra, "sierra3": dither.Sierra3, "tworowsierra": dither.TwoRowSierra, "sierralite": dither.SierraLite, "sierra2_4a": dither.Sierra2_4A, "stevenpigeon": dither.StevenPigeon, } func edm(c *cli.Context) error { args := c.Args().Slice() if len(args) != 1 { return errors.New("edm only accepts one argument") } var matrix dither.ErrorDiffusionMatrix matrix, ok := edmName[strings.ReplaceAll(strings.ToLower(args[0]), "-", "_")] if !ok { // Either inline JSON, path to file, or an error err := json.Unmarshal([]byte(args[0]), &matrix) if err != nil { bytes, err := ioutil.ReadFile(args[0]) if err != nil { return errors.New("couldn't process argument as matrix name, inline JSON, or path to accessible JSON file") } err = json.Unmarshal(bytes, &matrix) if err != nil { return errors.New("couldn't process argument as matrix name, inline JSON, or path to accessible JSON file") } } // Validate matrix if len(matrix) == 0 { return errors.New("matrix is empty") } // Is it rectangular? width := len(matrix[0]) if width == 0 { return errors.New("matrix has empty row") } for _, row := range matrix { if len(row) != width { return errors.New("matrix is not rectangular, all rows must be the same length") } } } ditherer.Matrix = dither.ErrorDiffusionStrength(matrix, strength) if c.Bool("serpentine") { ditherer.Serpentine = true } err := processImages(ditherer, c) if err != nil { return err } return nil }