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Bumps [github.com/kovidgoyal/imaging](https://github.com/kovidgoyal/imaging) from 1.7.2 to 1.8.17. - [Release notes](https://github.com/kovidgoyal/imaging/releases) - [Changelog](https://github.com/kovidgoyal/imaging/blob/master/.goreleaser.yaml) - [Commits](https://github.com/kovidgoyal/imaging/compare/v1.7.2...v1.8.17) --- updated-dependencies: - dependency-name: github.com/kovidgoyal/imaging dependency-version: 1.8.17 dependency-type: direct:production update-type: version-update:semver-minor ... Signed-off-by: dependabot[bot] <support@github.com>
157 lines
6.7 KiB
Markdown
157 lines
6.7 KiB
Markdown
# Imaging
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This is pure Go code that makes working with images actually
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useable on top of the Go stdlib. In addition to the usual PNG/JPEG/WebP/TIFF/BMP/GIF
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formats that have been supported forever, this package adds support for
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animated PNG, animated WebP, Google's new "jpegli" JPEG variant
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and all the netPBM image formats.
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Additionally, this package support color management via ICC profiles and CICP
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metadata. Opening non-sRGB images automatically converts them to sRGB, so you
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don't have to think about it. It has full support for ICC v2 and v4 profiles
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embedded in all the image formats and is extensively tested against the
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little-cms library.
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It also supports loading image metadata in EXIF format and automatically
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supports the EXIF orientation flag -- on image load the image is transformed
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based on that tag automatically.
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It automatically falls back to ImageMagick when available, for image formats
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it does not support.
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Finally, it provides basic image processing functions
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(resize, rotate, crop, brightness/contrast adjustments, etc.).
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## Installation
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go get -u github.com/kovidgoyal/imaging
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## Documentation
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https://pkg.go.dev/github.com/kovidgoyal/imaging
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## Quickstart
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```go
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img, metadata, err := imaging.OpenAll(path, options...)
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img.Resize(128, 128, imaging.Lanczos)
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img.SaveAsPNG(path, mode)
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```
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There are also convenience scripts that demonstrate this library in action,
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note that these are mainly for development and as such they only use the pure
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Go code and do not fallback to ImageMagick:
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```sh
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./to-png some-image.whatever some-image.png
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./to-frames some-animated-image.whatever some-animated-image.apng
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```
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Imaging supports image resizing using various resampling filters. The most notable ones:
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- `Lanczos` - A high-quality resampling filter for photographic images yielding sharp results.
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- `CatmullRom` - A sharp cubic filter that is faster than Lanczos filter while providing similar results.
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- `MitchellNetravali` - A cubic filter that produces smoother results with less ringing artifacts than CatmullRom.
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- `Linear` - Bilinear resampling filter, produces smooth output. Faster than cubic filters.
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- `Box` - Simple and fast averaging filter appropriate for downscaling. When upscaling it's similar to NearestNeighbor.
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- `NearestNeighbor` - Fastest resampling filter, no antialiasing.
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The full list of supported filters: NearestNeighbor, Box, Linear, Hermite, MitchellNetravali, CatmullRom, BSpline, Gaussian, Lanczos, Hann, Hamming, Blackman, Bartlett, Welch, Cosine. Custom filters can be created using ResampleFilter struct.
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**Resampling filters comparison**
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Original image:
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The same image resized from 600x400px to 150x100px using different resampling filters.
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From faster (lower quality) to slower (higher quality):
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Filter | Resize result
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--------------------------|---------------------------------------------
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`imaging.NearestNeighbor` | 
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`imaging.Linear` | 
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`imaging.CatmullRom` | 
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`imaging.Lanczos` | 
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### Gaussian Blur
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```go
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dstImage := imaging.Blur(srcImage, 0.5)
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```
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Sigma parameter allows to control the strength of the blurring effect.
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Original image | Sigma = 0.5 | Sigma = 1.5
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-----------------------------------|----------------------------------------|---------------------------------------
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### Sharpening
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```go
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dstImage := imaging.Sharpen(srcImage, 0.5)
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```
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`Sharpen` uses gaussian function internally. Sigma parameter allows to control the strength of the sharpening effect.
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Original image | Sigma = 0.5 | Sigma = 1.5
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-----------------------------------|-------------------------------------------|------------------------------------------
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### Gamma correction
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```go
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dstImage := imaging.AdjustGamma(srcImage, 0.75)
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```
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Original image | Gamma = 0.75 | Gamma = 1.25
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-----------------------------------|------------------------------------------|-----------------------------------------
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### Contrast adjustment
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```go
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dstImage := imaging.AdjustContrast(srcImage, 20)
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```
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Original image | Contrast = 15 | Contrast = -15
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-----------------------------------|--------------------------------------------|-------------------------------------------
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### Brightness adjustment
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```go
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dstImage := imaging.AdjustBrightness(srcImage, 20)
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```
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Original image | Brightness = 10 | Brightness = -10
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-----------------------------------|----------------------------------------------|---------------------------------------------
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### Saturation adjustment
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```go
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dstImage := imaging.AdjustSaturation(srcImage, 20)
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```
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Original image | Saturation = 30 | Saturation = -30
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-----------------------------------|----------------------------------------------|---------------------------------------------
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### Hue adjustment
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```go
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dstImage := imaging.AdjustHue(srcImage, 20)
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```
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Original image | Hue = 60 | Hue = -60
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-----------------------------------|----------------------------------------------|---------------------------------------------
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## Acknowledgements
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This is a fork of the un-maintained distraction/imaging project. The color
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management code was started out from mandykoh/prism and used some code from
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go-andiamo/iccarus but it was almost completely re-written from scratch.
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