chenglouPNG Diff
Small PNG diff utility, written in pure JS for Node.
npm install png-diffUsage
(Check out the example folder.)
Both methods take two image paths/streams/buffers as input.
var fs = require('fs');
var PNGDiff = require('png-diff');
var image2Stream = fs.createReadStream('2.png');
PNGDiff.outputDiff('1.png', image2Stream, 'diffOutput.png', function(err, diffMetric) {
if (err) throw err;
// returns 0 if every pixel's the same; return 1 otherwise. Currently, these
// are the only two possible metric values; possibility to tweak them in the
// future
console.log(diffMetric === 1 ? 'Difference detected.' : 'No difference');
// highlights the difference in red
console.log('Diff saved!');
});
var image1Buffer = fs.createReadStream('1.png');
PNGDiff.outputDiffStream(image1Buffer, '2.png', function(err, outputStream, diffMetric) {
if (err) throw err;
if (diffMetric === 0) {
console.log('No difference, no need to output diff result.');
return;
}
outputStream.pipe(fs.createWriteStream('diffOutput2.png'));
});Second format:
var image2Stream = fs.createReadStream('2.png');
// output identical pixels as transparent instead of highlighting the diff
// (default: false)
PNGDiff.outputDiff('1.png', image2Stream, 'diffOutput.png', true , function(err, diffMetric) {
if (err) throw err;
console.log(diffMetric === 1 ? 'Difference detected.' : 'No difference');
// does not highlight the difference, but replaces common pixels with
// transparent ones
console.log('Diff saved!');
});License
MIT.