The WEBGL_compressed_texture_s3tc_srgb extension is part of the WebGL API and exposes four S3TC compressed texture formats for the sRGB colorspace.

Compressed textures reduce the amount of memory needed to store a texture on the GPU, allowing for higher resolution textures or more of the same resolution textures.

WebGL extensions are available using the WebGLRenderingContext.getExtension() method. For more information, see also Using Extensions in the WebGL tutorial.

Availability: This extension is available to both WebGL1 and WebGL2 contexts.


The compressed texture formats are exposed by four constants and can be used in two functions: compressedTexImage2D() and compressedTexSubImage2D().

A DXT1-compressed image in an sRGB image format.
A DXT1-compressed image in an sRGB image format with a simple on/off alpha value.
A DXT3-compressed image in an sRGBA image format.
A DXT5-compressed image in an sRGBA image format.


var ext = gl.getExtension('WEBGL_compressed_texture_s3tc_srgb');

var texture = gl.createTexture();
gl.bindTexture(gl.TEXTURE_2D, texture);

gl.compressedTexImage2D(gl.TEXTURE_2D, 0, ext.COMPRESSED_SRGB_S3TC_DXT1_EXT, 512, 512, 0, textureData);

gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.LINEAR);
gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.LINEAR);


Specification Status Comment
The definition of 'WEBGL_compressed_texture_s3tc_srgb' in that specification.
Recommendation Initial definition.

Browser compatibility

ChromeEdgeFirefoxInternet ExplorerOperaSafariAndroid webviewChrome for AndroidFirefox for AndroidOpera for AndroidSafari on iOSSamsung Internet
WEBGL_compressed_texture_s3tc_srgbChrome Full support YesEdge Full support ≤79Firefox Full support 55IE ? Opera Full support YesSafari ? WebView Android Full support YesChrome Android Full support YesFirefox Android ? Opera Android Full support YesSafari iOS ? Samsung Internet Android Full support Yes


Full support
Full support
Compatibility unknown
Compatibility unknown

See also