HTML Canvas - createImageData() Method

Quiz

The HTML Canvas createImageData() method of Canvas 2D API creates an ImageData object in the Canvas element.

Syntax

Following is the syntax of HTML Canvas createImageData() method −

CanvasRenderingContext2D.createImageData(data, width, height);

Parameters

Following is the list of parameters of this method −

S.No	Parameter & Description
1	width The width value which is given to the ImageData object.
2	height The width value which is passed to the ImageData object.
3	data This data object is an existing ImageData object from which the properties such as width and height are copied into new object.

S.No

Parameter & Description

width

The width value which is given to the ImageData object.

height

The width value which is passed to the ImageData object.

data

This data object is an existing ImageData object from which the properties such as width and height are copied into new object.

Return value

A new ImageData object is created with specified height and width. It is filled with transparent black pixels by default.

Example

The following example creates a blank ImageData object using the HTML Canvas createImageData() method and returns its values using window alert.

<!DOCTYPE html>
<html lang="en">
<head>
   <title>Reference API</title>
   <style>
      body {
         margin: 10px;
         padding: 10px;
      }
   </style>
</head>
<body>
   <canvas id="canvas" width="400" height="200" style="border: 1px solid black;"></canvas>
   <script>
      var canvas = document.getElementById('canvas');
      var context = canvas.getContext('2d');
      var imgdata = context.createImageData(55, 55);
      console.log(imgdata);
   </script>
</body>
</html>

Output

The output returned by the image on the webpage as −

The data shown in the console as −

Example

The following example demonstrates how an Image data object is created and styled inside the Canvas element using the HTML Canvas createImageData() method.

<!DOCTYPE html>
<html lang="en">
<head>
   <title>Reference API</title>
   <style>
      body {
         margin: 10px;
         padding: 10px;
      }
   </style>
</head>
<body onload="Context();">
   <canvas id="canvas" width="300" height="200" style="border: 1px solid black;"></canvas>
   <script>
      function Context() {
         var canvas = document.getElementById('canvas');
         var context = canvas.getContext('2d');
         var i, imageData = context.createImageData(100, 100);
         for (i = 0; i < imageData.data.length; i += 4) {
            imageData.data[i + 0] = 200;
            imageData.data[i + 1] = 100;
            imageData.data[i + 2] = 100;
            imageData.data[i + 3] = 200;
         }
         context.putImageData(imageData, 15, 15);
      }
   </script>
</body>
</html>

Output

The output returned by the image on the webpage as −

html_canvas_images.htm

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