avoid interference with backwards compatibility gamma input/output.

examples/js/pmrem/PMREMGenerator.js

@@ -63,6 +63,11 @@ THREE.PMREMGenerator.prototype = {
 
 		this.shader.uniforms[ "envMap" ].value = this.sourceTexture;
     this.shader.envMap = this.sourceTexture;
+
+    var gammaInput = renderer.gammaInput;
+    var gammaOutput = renderer.gammaOutput;
+    renderer.gammaInput = false;
+    renderer.gammaOutput = false;
 		for ( var i = 0; i < this.numLods; i ++ ) {
 
 			var r = i / ( this.numLods - 1 );
@@ -75,6 +80,9 @@ THREE.PMREMGenerator.prototype = {
 
 		}
 
+    renderer.gammaInput = renderer.gammaInput;
+    renderer.gammaOutput = renderer.gammaOutput;
+    
 	},
 
 	renderToCubeMapTarget: function( renderer, renderTarget ) {

examples/js/pmrem/PMREM_CubeUVPacker.js

@@ -98,8 +98,16 @@ THREE.PMREM_CubeUVPacker.prototype = {
 
 	update: function( renderer ) {
 
+		var gammaInput = renderer.gammaInput;
+    var gammaOutput = renderer.gammaOutput;
+    renderer.gammaInput = false;
+    renderer.gammaOutput = false;
+
 		renderer.render( this.scene, this.camera, this.CubeUVRenderTarget, true );
 
+    renderer.gammaInput = renderer.gammaInput;
+    renderer.gammaOutput = renderer.gammaOutput;
+
 	},
 
   getShader: function() {