gistfile1.js

generateClickMap:function (image) {
    var imageData, data, width, height;

    var c = document.createElement('canvas');
    var ctx = c.getContext('2d');
    var clickMap = [];

    width = image.width;
    height = image.height;
    c.width = width;
    c.height = height;

    ctx.drawImage(image, 0, 0);

    imageData = ctx.getImageData(0, 0, width, height);
    data = imageData.data;

    for (var i = 0, n = data.length; i < n; i += 4) {
        var row = Math.floor((i / 4) / width);
        var col = (i / 4) - (row * width);
        if (!clickMap[row]) clickMap[row] = [];
        clickMap[row][col] = data[i + 3] == 0 ? 0 : 1;
    }

    return clickMap;
}