WebGLImageFilter

Construct a chain of image filters and apply them to an Image or Canvas element. All filters are executed by WebGL Shaders which makes them pretty fast.

Demo: phoboslab.org/log/2013/11/webgl-image-filter

Please also have a look at the excellent glfx.js by @evanw.

Usage

// Synopsis: create the filter object, add filters to it and apply
// it to an image

// Example:
try {
	var filter = new WebGLImageFilter();
}
catch( err ) {
	// Handle browsers that don't support WebGL
}

filter.addFilter('hue', 180);
filter.addFilter('negative');
filter.addFilter('blur', 7);

// inputImage may be an Image, or even an HTML Canvas!
var filteredImage = filter.apply(inputImage);

// The 'filteredImage' is a canvas element. You can draw it on a 2D canvas
// or just add it to your DOM

// Use .reset() to clear the current filter chain. This is faster than creating a new
// WebGLImageFilter instance
filter.reset();

Using an Existing Canvas element

Internally, WebGLImageFilter creates one canvas element, which is what the output filtered result is written to. If you have an existing canvas element that you want to render to, you can configure WebGLImageFilter to use it:

try {
	// in this case, filteredImage is an existing html canvas
	var filter = new WebGLImageFilter({ canvas: filteredImage });
}
catch( err ) { }

// .. filters setup here

filter.apply(inputImage); 

// at this point, filteredImage has already been updated

Filters

Main filters

colorMatrix( matrix ) apply a the 5x5 color matrix (Array[20]), similar to Flash's ColorMatrixFilter
convolution( matrix ) apply a 3x3 convolution matrix (Array[9])
blur( radius ) blur with radius in pixels

Presets using the main filters

brightness( amount ) change brightness. 1 increases the it two fold, -1 halves it
saturation( amount ) change saturation. 1 increases the it two fold, -1 halves it
contrast( amount ) change contrast. 1 increases the it two fold, -1 halves it
negative() invert colors
hue( rotation ) rotate the hue, values are 0-360
desaturate() desaturate the image by all channels equally
desaturateLuminance() desaturate the image taking the natural luminace of each channel into acocunt
sepia() sepia colors
brownie() vintage colors
vintagePinhole() vintage colors
kodachrome() vintage colors
technicolor() vintage colors
detectEdges() detect edges
sobelX() detect edges using a horizontal sobel operator
sobelY() detect edges using a vertical sobel operator
sharpen( amount ) sharpen
emboss( size ) emboss effect with size in pixels
polaroid() polaroid camera effect
shiftToBGR() shift colors from RGB to BGR
pixelate(amount) pixelate

License

MIT