three.js/examples/js/shaders/TechnicolorShader.js

/**
 * Technicolor Shader
 * Simulates the look of the two-strip technicolor process popular in early 20th century films.
 * More historical info here: http://www.widescreenmuseum.com/oldcolor/technicolor1.htm
 * Demo here: http://charliehoey.com/technicolor_shader/shader_test.html
 */

THREE.TechnicolorShader = {

	uniforms: {

		'tDiffuse': { value: null }

	},

	vertexShader: [

		'varying vec2 vUv;',

		'void main() {',

		'	vUv = uv;',
		'	gl_Position = projectionMatrix * modelViewMatrix * vec4( position, 1.0 );',

		'}'

	].join( '\n' ),

	fragmentShader: [

		'uniform sampler2D tDiffuse;',
		'varying vec2 vUv;',

		'void main() {',

		'	vec4 tex = texture2D( tDiffuse, vec2( vUv.x, vUv.y ) );',
		'	vec4 newTex = vec4(tex.r, (tex.g + tex.b) * .5, (tex.g + tex.b) * .5, 1.0);',

		'	gl_FragColor = newTex;',

		'}'

	].join( '\n' )

};