通过Javascript获取图像的平均颜色 [英] Get average color of image via Javascript

问题描述

不确定这是否可行，但希望编写一个脚本，该脚本将返回平均值 hex 或 rgb 值对于图像。我知道它可以在AS中完成，但希望在JavaScript中完成。

Not sure this is possible, but looking to write a script that would return the average hex or rgb value for an image. I know it can be done in AS but looking to do it in JavaScript.

推荐答案

AFAIK，唯一的方法是使用< canvas /> ...

AFAIK, the only way to do this is with <canvas/>...

DEMO V2 ： http://jsfiddle.net/xLF38/818/

注意，这只适用于相同的域和支持HTML5画布的浏览器：

Note, this will only work with images on the same domain and in browsers that support HTML5 canvas:

function getAverageRGB(imgEl) {

    var blockSize = 5, // only visit every 5 pixels
        defaultRGB = {r:0,g:0,b:0}, // for non-supporting envs
        canvas = document.createElement('canvas'),
        context = canvas.getContext && canvas.getContext('2d'),
        data, width, height,
        i = -4,
        length,
        rgb = {r:0,g:0,b:0},
        count = 0;

    if (!context) {
        return defaultRGB;
    }

    height = canvas.height = imgEl.naturalHeight || imgEl.offsetHeight || imgEl.height;
    width = canvas.width = imgEl.naturalWidth || imgEl.offsetWidth || imgEl.width;

    context.drawImage(imgEl, 0, 0);

    try {
        data = context.getImageData(0, 0, width, height);
    } catch(e) {
        /* security error, img on diff domain */
        return defaultRGB;
    }

    length = data.data.length;

    while ( (i += blockSize * 4) < length ) {
        ++count;
        rgb.r += data.data[i];
        rgb.g += data.data[i+1];
        rgb.b += data.data[i+2];
    }

    // ~~ used to floor values
    rgb.r = ~~(rgb.r/count);
    rgb.g = ~~(rgb.g/count);
    rgb.b = ~~(rgb.b/count);

    return rgb;

}

对于IE，请查看 excanvas 。

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