three.js/examples/js/shaders/BrightnessContrastShader.js

( function () {

	/**
 * Brightness and contrast adjustment
 * https://github.com/evanw/glfx.js
 * brightness: -1 to 1 (-1 is solid black, 0 is no change, and 1 is solid white)
 * contrast: -1 to 1 (-1 is solid gray, 0 is no change, and 1 is maximum contrast)
 */
	var BrightnessContrastShader = {
		uniforms: {
			'tDiffuse': {
				value: null
			},
			'brightness': {
				value: 0
			},
			'contrast': {
				value: 0
			}
		},
		vertexShader: [ 'varying vec2 vUv;', 'void main() {', '	vUv = uv;', '	gl_Position = projectionMatrix * modelViewMatrix * vec4( position, 1.0 );', '}' ].join( '\n' ),
		fragmentShader: [ 'uniform sampler2D tDiffuse;', 'uniform float brightness;', 'uniform float contrast;', 'varying vec2 vUv;', 'void main() {', '	gl_FragColor = texture2D( tDiffuse, vUv );', '	gl_FragColor.rgb += brightness;', '	if (contrast > 0.0) {', '		gl_FragColor.rgb = (gl_FragColor.rgb - 0.5) / (1.0 - contrast) + 0.5;', '	} else {', '		gl_FragColor.rgb = (gl_FragColor.rgb - 0.5) * (1.0 + contrast) + 0.5;', '	}', '}' ].join( '\n' )
	};

	THREE.BrightnessContrastShader = BrightnessContrastShader;

} )();