three.js/examples/js/shaders/GammaCorrectionShader.js

( function () {

	/**
 * Gamma Correction Shader
 * http://en.wikipedia.org/wiki/gamma_correction
 */
	const GammaCorrectionShader = {
		uniforms: {
			'tDiffuse': {
				value: null
			}
		},
		vertexShader: `varying vec2 vUv;

		void main() {

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

		}`,
		fragmentShader: `uniform sampler2D tDiffuse;

		varying vec2 vUv;

		void main() {

			vec4 tex = texture2D( tDiffuse, vUv );

			gl_FragColor = LinearTosRGB( tex ); // optional: LinearToGamma( tex, float( GAMMA_FACTOR ) );

		}`
	};

	THREE.GammaCorrectionShader = GammaCorrectionShader;

} )();