CanvasRenderingContext2D: getImageData() method
===============================================

 The `CanvasRenderingContext2D` method
 **`getImageData()`** of the Canvas 2D API returns an
 `ImageData` object representing the underlying pixel data for a specified
 portion of the canvas.

 This method is not affected by the canvas's transformation matrix. If the specified
 rectangle extends outside the bounds of the canvas, the pixels outside the canvas are
 transparent black in the returned `ImageData` object.


**Note:** Image data can be painted onto a canvas using the
 `putImageData()` method.


 You can find more information about `getImageData()` and general
 manipulation of canvas contents in Pixel manipulation with canvas.

Syntax
------


```js
getImageData(sx, sy, sw, sh)
getImageData(sx, sy, sw, sh, settings)
```

### Parameters

`sx`

 The x-axis coordinate of the top-left corner of the rectangle from which the
 `ImageData` will be extracted.


`sy`

 The y-axis coordinate of the top-left corner of the rectangle from which the
 `ImageData` will be extracted.


`sw`

 The width of the rectangle from which the `ImageData` will be extracted.
 Positive values are to the right, and negative to the left.


`sh`

 The height of the rectangle from which the `ImageData` will be extracted.
 Positive values are down, and negative are up.


`settings` Optional

An object with the following properties:

* `colorSpace`: Specifies the color space of the image data. Can be set to `"srgb"` for the sRGB color space or `"display-p3"` for the display-p3 color space.

### Return value

 An `ImageData` object containing the image data for the rectangle of the
 canvas specified. The coordinates of the rectangle's top-left corner are
 `(sx, sy)`, while the coordinates of the bottom corner are
 `(sx + sw - 1, sy + sh - 1)`.

### Exceptions

`IndexSizeError` `DOMException`

Thrown if either `sw` or `sh` are zero.

`SecurityError` `DOMException`

 The canvas contains or may contain pixels which were loaded from an origin other
 than the one from which the document itself was loaded.
 To avoid a `SecurityError` `DOMException` being thrown in this situation,
 configure CORS to allow the source image to be used in this way.
 See Allowing cross-origin use of images and canvas.


Examples
--------

### Getting image data from a canvas

 This example draws an image, and then uses `getImageData()` to grab a
 portion of the canvas.

We use `getImageData()` to extract a slice of the image, starting at `(10, 20)`, with a width of `80` and a height of `230`. We then draw this slice three times, positioning the slices progressively below and to the right of the last slice.

#### HTML


```html
<canvas id="canvas" width="700" height="400"></canvas>
```


#### JavaScript


```js
const canvas = document.getElementById("canvas");
const ctx = canvas.getContext("2d");

const image = new Image();
image.src = "plumeria.jpg";
image.addEventListener("load", () => {
  ctx.drawImage(image, 0, 0, 233, 320);

  const imageData = ctx.getImageData(10, 20, 80, 230);
  ctx.putImageData(imageData, 260, 0);
  ctx.putImageData(imageData, 380, 50);
  ctx.putImageData(imageData, 500, 100);
});
```


#### Result

### Color space conversion

The optional `colorSpace` setting allows you to get image data in the desired format.


```js
const context = canvas.getContext("2d", { colorSpace: "display-p3" });
context.fillStyle = "color(display-p3 0.5 0 0)";
context.fillRect(0, 0, 10, 10);

// Get ImageData converted to sRGB
const imageData = context.getImageData(0, 0, 1, 1, { colorSpace: "srgb" });
console.log(imageData.colorSpace); // "srgb"
```

Specifications
--------------

| Specification |
| --- |
| HTML Standard # dom-context-2d-getimagedata-dev |

Browser compatibility
---------------------

BCD tables only load in the browser with JavaScript enabled. Enable JavaScript to view data.

See also
--------

* The interface defining this method: `CanvasRenderingContext2D`
* `ImageData` object
* `CanvasRenderingContext2D.putImageData()`
* Pixel manipulation with canvas