Canvas reference: The getImageData() function

The getImageData() function allows to retrieve an ImageData object from your canvas. This allows you to manipulate it as you wish and then you can add it back on to the canvas with the putImageData() function. You can pass it the X/Y/W/H that you want to fetch as arguments.

Arguments to the function

• The X coordinate at which to fetching data
• The Y coordinate at which to fetching data
• The width to fetch
• The height to fetch

An example

<script>
    window.onload = function ()
    {
        var canvas = document.getElementById('cvs');
        var context = canvas.getContext('2d');
        
        // Fetches image data from the canvas
        var imgData = context.getImageData(0,0,600,250);
    }
</script>