image-ms-ssim/index.ts

Image multi-scale structural similarity (MS-SSIM). In TypeScript/JavaScript. For browser/server.

//
// Copyright(c) Multimedia Signal Processing Group (MMSPG),
//              Ecole Polytechnique Fédérale de Lausanne (EPFL)
//              http://mmspg.epfl.ch
//              Zhou Wang
//              https://ece.uwaterloo.ca/~z70wang/
// All rights reserved.
// Author: Philippe Hanhart (philippe.hanhart@epfl.ch)
//
// Permission is hereby granted, without written agreement and without
// license or royalty fees, to use, copy, modify, and distribute the
// software provided and its documentation for research purpose only,
// provided that this copyright notice and the original authors' names
// appear on all copies and supporting documentation.
// The software provided may not be commercially distributed.
// In no event shall the Ecole Polytechnique Fédérale de Lausanne (EPFL)
// be liable to any party for direct, indirect, special, incidental, or
// consequential damages arising out of the use of the software and its
// documentation.
// The Ecole Polytechnique Fédérale de Lausanne (EPFL) specifically
// disclaims any warranties.
// The software provided hereunder is on an "as is" basis and the Ecole
// Polytechnique Fédérale de Lausanne (EPFL) has no obligation to provide
// maintenance, support, updates, enhancements, or modifications.
//

//
// Original Matlab implementation from Nikolay Ponomarenko available from http://live.ece.utexas.edu/research/quality/.
// Please refer to the following papers:
// - Z. Wang, E.P. Simoncelli, and A.C. Bovik, "Multiscale structural
//   similarity for image quality assessment," in IEEE Asilomar Conference
//   on Signals, Systems and Computers, November 2003, vol. 2, pp. 1398–1402.
//

/**
 * Based on:
 * - C++ implementation https://github.com/Rolinh/VQMT/blob/master/src/MSSSIM.cpp
 * - TypeScript implementation: https://github.com/darosh/image-ssim-js
 */

/// <reference path="node_modules/image-ssim/image-ssim.d.ts" />
/// <reference path="node_modules/image-resize-linear/image-resize-linear.d.ts" />

import SSIM = require('image-ssim');
import IR = require('image-resize-linear');

module ImageMSSSIM {
	'use strict';

	export type Data = number[]|any[]|Uint8Array;

	/**
	 * Grey = 1, GreyAlpha = 2, RGB = 3, RGBAlpha = 4
	 */
	export type Channels = number;

	export interface IImage {
		data:Data;
		width:number;
		height:number;
		channels:Channels;
	}

	export interface IResult {
		msssim: number;
		ssim:number;
	}

	/**
	 * Entry point.
	 */
	export function compare(image1:IImage,
							image2:IImage,
							windowSize:number = 8,
							K1:number = 0.01,
							K2:number = 0.03,
							luminance:boolean = true,
							bitsPerComponent:number = 8):IResult {
		var WEIGHT:number[] = [0.0448, 0.2856, 0.3001, 0.2363, 0.1333];

		var mssim:number[] = [];
		var mcs:number[] = [];

		var im1:IImage[] = [];
		var im2:IImage[] = [];

		var w:number = image1.width;
		var h:number = image1.height;

		im1[0] = image1;
		im2[0] = image2;

		for (var l:number = 0; l < WEIGHT.length; l++) {
			var res:any = SSIM.compare(<any>im1[l],
				<any>im2[l],
				windowSize,
				K1,
				K2,
				luminance,
				bitsPerComponent);

			mssim[l] = res.ssim;
			mcs[l] = res.mcs;

			if (l < WEIGHT.length - 1) {
				w = Math.floor(w / 2);
				h = Math.floor(h / 2);
				im1[l + 1] = {
					width: w,
					height: h,
					data: new Uint8Array(w * h * image1.channels),
					channels: image1.channels
				};
				im2[l + 1] = {
					width: w,
					height: h,
					data: new Uint8Array(w * h * image2.channels),
					channels: image2.channels
				};
				IR.linear(im1[l], im1[l + 1]);
				IR.linear(im2[l], im2[l + 1]);
			}
		}

		var msssim:number = mssim[WEIGHT.length - 1];

		for (l = 0; l < WEIGHT.length - 1; l++) {
			msssim *= Math.pow(mcs[l], WEIGHT[l]);
		}

		return {msssim: msssim, ssim: mssim[0]};
	}
}

export = ImageMSSSIM;