使用getImageData获取RGB值

Question

我正在读取图像的所有像素，我正在尝试获取像素的rgb值并更改此值。目前我只得到1个变量。从1到255不等。但我似乎无法获得3个值。我究竟做错了什么？

<script>
var effectButton;
var paintButton;
var canvas;
var context;

function init()
{
    var image = document.getElementById('SourceImage');
    effectButton = document.getElementById('EffectButton');
    paintButton = document.getElementById('PaintButton');
    canvas = document.getElementById('Canvas');
    context = canvas.getContext('2d');

    // Set the canvas the same width and height of the image
    canvas.width = image.width;
    canvas.height = image.height;

    paintButton.addEventListener('click', function ()
    {
        drawImage(image);
    });

    effectButton.addEventListener('click', addEffect);
}

function drawImage(image)
{
  context.drawImage(image, 0, 0);
}

function addEffect()
{
    var imageData = context.getImageData(0, 0, canvas.width, canvas.height);
    MakeMoreRed(imageData.data);
    context.putImageData(imageData, 0, 0);
}

function MakeMoreRed(data)
{
    for (var i = 0; i < data.length; i++ )
    {
        //How do i get the rgb value?? from data[i]
        data[i] = data[i] + 5;

        //var green = data[i] + 5;
        //var blue= data[i] + 5;
    }
}

window.addEventListener('load', init);

</script>

Answer 1

弄清楚了。数据基本上是一个庞大的数组。 data [0]是第一个像素的红色值，data [1]是第一个像素的绿色值，data [2]是第一个像素的蓝色值，data [3]是第一个像素的不透明度值像素。

知道这一点，我做了一个for循环来遍历每个像素。

function MakeMoreRed(data)
{
var index;

for(var y = 0; y < canvas.height; y++ )
{
    for(var x = 0; x < canvas.width; x++ )
    {
        index = (x + y * canvas.width)*4;

        data[index+0] = data[index+0] + 5;
        data[index+1] = 0;
        data[index+2] = 0;
        data[index+3] = 255;
    }
}

}