glsl-film-grain

glsl-film-grain

(click for demo)

Natural looking film grain using 3D noise functions. Inspired by Martins Upitis.

This is a fairly expensive technique to achieve film grain, but it looks more realistic than a hash function and also produces better motion.

Simplest example:

#pragma glslify: grain = require(glsl-film-grain)

void main() {
    float grainSize = 2.0;
    float g = grain(texCoord, resolution / grainSize);
    vec3 color = vec3(g);
    gl_FragColor = vec4(color, 1.0);
}

Results in:

See blending tips and the demo source for details.

Usage

f = grain(texCoord, resolution[, frame[, q]])

Returns a float for the monochromatic grain with the given options:

• texCoord the UV coordinates of your scene
• resolution the resolution of your scene in pixels, optionally scaled to adjust the grain size
• frame the animation frame, which is an offset into the Z of the 3D noise
• q is a coefficient for the offset calculation, and may evoke subtly different motion. Defaults to 2.5

blending tips

There are a lot of ways to blend the noise onto the 3D scene or image. The solution used in the demo uses glsl-blend-soft-light and glsl-luma.

    vec3 g = vec3(grain(texCoord, p));
  
    //blend the noise over the background, 
    //i.e. overlay, soft light, additive
    vec3 color = blend(backgroundColor, g);
    
    //get the luminance of the background
    float luminance = luma(backgroundColor);
    
    //reduce the noise based on some 
    //threshold of the background luminance
    float response = smoothstep(0.05, 0.5, luminance);
    color = mix(color, backgroundColor, pow(response, 2.0));
    
    //final color
    gl_FragColor = vec4(color, 1.0);

License

MIT, see LICENSE.md for details.