fabric/src/filters/shaders/vibrance.ts

Object model for HTML5 canvas, and SVG-to-canvas parser. Backed by jsdom and node-canvas.

export const fragmentSource = `
  precision highp float;
  uniform sampler2D uTexture;
  uniform float uVibrance;
  varying vec2 vTexCoord;
  void main() {
    vec4 color = texture2D(uTexture, vTexCoord);
    float max = max(color.r, max(color.g, color.b));
    float avg = (color.r + color.g + color.b) / 3.0;
    float amt = (abs(max - avg) * 2.0) * uVibrance;
    color.r += max != color.r ? (max - color.r) * amt : 0.00;
    color.g += max != color.g ? (max - color.g) * amt : 0.00;
    color.b += max != color.b ? (max - color.b) * amt : 0.00;
    gl_FragColor = color;
  }
`;