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smartcrop finds good image crops for arbitrary sizes. It is a pure Go implementation, based on Jonas Wagner’s smartcrop.js

Example Image: by Washington Dept of Fish and Wildlife, originally licensed under CC-BY-2.0 when the image was imported back in September 2014

Example Image: by Leon F. Cabeiro (N. Feans), licensed under CC-BY-2.0


Make sure you have a working Go environment (Go 1.9 or higher is required). See the install instructions.

To install smartcrop, simply run:

go get

To compile it from source:

cd $GOPATH/src/
go get -u -v
go build && go test -v


package main

import (
	_ "image/png"


func main() {
	f, _ := os.Open("image.png")
	img, _, _ := image.Decode(f)

	analyzer := smartcrop.NewAnalyzer(nfnt.NewDefaultResizer())
	topCrop, _ := analyzer.FindBestCrop(img, 250, 250)

	// The crop will have the requested aspect ratio, but you need to copy/scale it yourself
	fmt.Printf("Top crop: %+v\n", topCrop)

	type SubImager interface {
		SubImage(r image.Rectangle) image.Image
	croppedimg := img.(SubImager).SubImage(topCrop)
	// ...

Also see the test cases in smartcrop_test.go and cli application in cmd/smartcrop/ for further working examples.

Simple CLI application

cd $GOPATH/src/  
go install ./cmd/smartcrop

Usage of smartcrop:
  -height int
        crop height
  -input string
        input filename
  -output string
        output filename
  -quality int
        jpeg quality (default 85)
        resize after cropping (default true)
  -width int
        crop width

Example: smartcrop -input examples/gopher.jpg -output gopher_cropped.jpg -width 300 -height 150

Sample Data

You can find a bunch of test images for the algorithm here.


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