从 HTML Canvas 获取像素？

W3C 文档中有一个关于像素操作的部分。

下面是如何反转图像的示例：

var context = document.getElementById('myCanvas').getContext('2d');

// Get the CanvasPixelArray from the given coordinates and dimensions.
var imgd = context.getImageData(x, y, width, height);
var pix = imgd.data;

// Loop over each pixel and invert the color.
for (var i = 0, n = pix.length; i < n; i += 4) {
    pix[i  ] = 255 - pix[i  ]; // red
    pix[i+1] = 255 - pix[i+1]; // green
    pix[i+2] = 255 - pix[i+2]; // blue
    // i+3 is alpha (the fourth element)
}

// Draw the ImageData at the given (x,y) coordinates.
context.putImageData(imgd, x, y);

请尝试 getImageData 方法：

var data = context.getImageData(x, y, 1, 1).data;
var rgb = [ data[0], data[1], data[2] ];