var context = null;

var image = null;

function loadImage() {

var main = document.getElementById("maincanvas");

if(main == null)

return false;

context = main.getContext("2d");

drawImage();

}

function drawImage() {

//反色效果

var imgSrc = document.getElementById("image");

context.drawImage(imgSrc, 0, 0);

var imgd = context.getImageData(0, 0, 398, 552);

var pix = imgd.data;

for(var i = 0, n = pix.length; i < n; i += 4) {

pix[i] = 255 - pix[i];

pix[i + 1] = 255 - pix[i + 1];

pix[i + 2] = 255 - pix[i + 2];

}

context.putImageData(imgd, 0, 0, 398, 552);

//透明度效果

var imgSrc_alpha = document.getElementById("image_alpha");

context.drawImage(imgSrc_alpha, 400, 0, 398, 552);

var imgd_alpha = context.getImageData(400, 0, 398, 552);

var pix_alpha = imgd_alpha.data;

for(var j = 3, n = pix_alpha.length; j < n; j += 4) {

pix_alpha[j] = pix_alpha[j] * 0.2;

}

context.putImageData(imgd_alpha, 400, 0, 398);

}

Sorry, your browser doesn't support canvas, please use Firefox3.6+, Safari5+, Chrome, IE9 etc.

也可以外部调用JS

// JavaScript Document

Main.js

var main ;

var context = null;

function loadImage() {

main = document.getElementById("maincanvas");

if(main == null)

return false;

context = main.getContext("2d");

drawImage();

}

function drawImage() {

var image = new Image();

image.src = "images/other/kboom.png";

image.onload = function() {

context.drawImage(image, 0, 0);

var imgd_alpha = context.getImageData(0, 0, 398, 552);

var pix_alpha = imgd_alpha.data;

for(var j = 3, n = pix_alpha.length; j < n; j += 4) {

pix_alpha[j] = pix_alpha[j] * 0.2;

}

context.putImageData(imgd_alpha, 0, 0);

};

}