Accessing Pixel Data in HTML Canvas

Is it possible to retrieve the color of a specific pixel within an HTML Canvas object? Yes, you can access and manipulate pixel data in HTML Canvas using various methods provided by the Canvas API.

Getting Pixel Color

To retrieve the color of a pixel at a specific location within a canvas, you can use the getImageData() method. This method returns an ImageData object that represents a portion of the canvas. The ImageData object contains an array of pixel data that you can access using the .data property.

Pixel Manipulation

Once you have obtained the pixel data, you can manipulate it as desired. For example, you can create a grayscale image by converting each pixel to a shade of gray:

// 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 convert it to grayscale.
for (var i = 0, n = pix.length; i < n; i  = 4) {
  var gray = (pix[i]   pix[i 1]   pix[i 2]) / 3;
  pix[i  ] = gray;
  pix[i 1] = gray;
  pix[i 2] = gray;
}

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

By leveraging the getImageData() and putImageData() methods, you can perform various pixel manipulation tasks, such as image filtering, color adjustments, and creating effects on HTML Canvas.