A simple Node.js script that uses GraphicsMagick (or ImageMagick) to perform image forensics on a JPEG. The script detects areas of a JPEG image that have been modified and highlights them in red.

image-forensics.js

var exec = require("child_process").exec;
var fs = require("fs");

exec("gm convert test.jpg -quality 95 new.jpg", function (error, stdout, stderr) {
  exec("gm compare -highlight-style Assign -highlight-color red -file out.jpg test.jpg new.jpg", function (error, stdout, stderr) {
    // Done.
  });
});