CanvasRenderingContext2D: filter property

The filter property accepts a value of "none" or one or more of the following filter functions in a string.

url()

A CSS url(). Takes an IRI pointing to an SVG filter element, which may be embedded in an external XML file.

blur()

A CSS <length>. Applies a Gaussian blur to the drawing. It defines the value of the standard deviation to the Gaussian function, i.e., how many pixels on the screen blend into each other; thus, a larger value will create more blur. A value of 0 leaves the input unchanged.

brightness()

A CSS <percentage>. Applies a linear multiplier to the drawing, making it appear brighter or darker. A value under 100% darkens the image, while a value over 100% brightens it. A value of 0% will create an image that is completely black, while a value of 100% leaves the input unchanged.

contrast()

A CSS <percentage>. Adjusts the contrast of the drawing. A value of 0% will create a drawing that is completely black. A value of 100% leaves the drawing unchanged.

drop-shadow()

Applies a drop shadow effect to the drawing. A drop shadow is effectively a blurred, offset version of the drawing's alpha mask drawn in a particular color, composited below the drawing. This function takes up to five arguments:

<offset-x>

See <length> for possible units. Specifies the horizontal distance of the shadow.

<offset-y>

See <length> for possible units. Specifies the vertical distance of the shadow.

<blur-radius>

The larger this value, the bigger the blur, so the shadow becomes bigger and lighter. Negative values are not allowed.

<color>

See <color> values for possible keywords and notations.

grayscale()

A CSS <percentage>. Converts the drawing to grayscale. A value of 100% is completely grayscale. A value of 0% leaves the drawing unchanged.

hue-rotate()

A CSS <angle>. Applies a hue rotation on the drawing. A value of 0deg leaves the input unchanged.

invert()

A CSS <percentage>. Inverts the drawing. A value of 100% means complete inversion. A value of 0% leaves the drawing unchanged.

opacity()

A CSS <percentage>. Applies transparency to the drawing. A value of 0% means completely transparent. A value of 100% leaves the drawing unchanged.

saturate()

A CSS <percentage>. Saturates the drawing. A value of 0% means completely un-saturated. A value of 100% leaves the drawing unchanged.

sepia()

A CSS <percentage>. Converts the drawing to sepia. A value of 100% means completely sepia. A value of 0% leaves the drawing unchanged.

none

No filter is applied. Initial value.

To view these examples, make sure to use a browser that supports this feature; see the compatibility table below.

This example blurs a piece of text using the filter property.

HTML

<canvas id="canvas"></canvas>

JavaScript

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

ctx.filter = "blur(4px)";
ctx.font = "48px serif";
ctx.fillText("Hello world", 50, 100);

Result

You can combine as many filters as you like. This example applies the contrast, sepia, and drop-shadow filters to a photo of a rhino.

HTML

<canvas id="canvas" width="400" height="150"></canvas>
<div style="display:none;">
  <img id="source" src="rhino.jpg" />
</div>

JavaScript

const canvas = document.getElementById("canvas");
const ctx = canvas.getContext("2d");
const image = document.getElementById("source");

image.addEventListener("load", (e) => {
  // Draw unfiltered image
  ctx.drawImage(image, 0, 0, image.width * 0.6, image.height * 0.6);

  // Draw image with filter
  ctx.filter = "contrast(1.4) sepia(1) drop-shadow(-9px 9px 3px #e81)";
  ctx.drawImage(image, 400, 0, -image.width * 0.6, image.height * 0.6);
});

Result

• The interface defining this property: CanvasRenderingContext2D
• CSS filter
• CSS <filter-function>