Image comparison using MagickWand/ImageMagick in Go

imagediff.go

package main

import (
	"log"

	"gopkg.in/gographics/imagick.v3/imagick"
)

func run(refFile, srcFile, prefix string) (err error) {
	refMW := imagick.NewMagickWand()
	defer refMW.Destroy()
	srcMW := imagick.NewMagickWand()
	defer srcMW.Destroy()

	err = refMW.ReadImage(refFile)
	if err != nil {
		return
	}
	err = srcMW.ReadImage(srcFile)
	if err != nil {
		return
	}

	err = srcMW.SetImageCompose(imagick.COMPOSITE_OP_SRC)
	if err != nil {
		return
	}
	diffFn := func(name string, metric imagick.MetricType) {
		diff, dist := srcMW.CompareImages(refMW, metric)
		log.Printf("Distortion (%s): %f", name, dist)
		defer diff.Destroy()
		diff.WriteImage(prefix + "-" + name + ".jpg")
	}
	for name, metric := range map[string]imagick.MetricType{
		"perceptual-hash-error":              imagick.METRIC_PERCEPTUAL_HASH_ERROR,
		"undefined":                          imagick.METRIC_UNDEFINED,
		"absolute-error":                     imagick.METRIC_ABSOLUTE_ERROR,
		"fuzz-error":                         imagick.METRIC_FUZZ_ERROR,
		"mean-absolute-error":                imagick.METRIC_MEAN_ABSOLUTE_ERROR,
		"mean-error-per-pixel":               imagick.METRIC_MEAN_ERROR_PER_PIXEL,
		"mean-squared-error":                 imagick.METRIC_MEAN_SQUARED_ERROR,
		"normalized-corss-correlation-error": imagick.METRIC_NORMALIZED_CROSS_CORRELATION_ERROR,
		"peak-absolute-error":                imagick.METRIC_PEAK_ABSOLUTE_ERROR,
		"peak-snr":                           imagick.METRIC_PEAK_SIGNAL_TO_NOISE_RATIO,
		"rms-error":                          imagick.METRIC_ROOT_MEAN_SQUARED_ERROR,
	} {
		diffFn(name, metric)
	}

	return nil
}

func main() {
	imagick.Initialize()
	defer imagick.Terminate()

	// This implements the following ImageMagick CLI command:
	// compare -compose src reference.jpg source.jpg diff.jpg
	run("reference.jpg", "source.jpg", "diff")
}