generator-scratch/app/templates/scratch/grunt/image.js

Scratch is a starter theme generator based on _s and Foundation. It's a theme meant for hacking so don't use it as a Parent Theme. Instead try turning it into the next, most awesome, WordPress theme out there.

module.exports = {
	/**
	 * grunt-image
	 *
	 * Optimize PNG, JPEG, GIF, SVG images with grunt task.
	 *
	 * @link https://www.npmjs.com/package/grunt-image
	 */
	images: {
		files: [{
			expand: true,
			cwd: 'src/img/',
			src: ['**/*.{png,jpg,gif,svg}'],
			dest: 'assets/img/'
		}]
	}
};