Ideally you would use the Desaturation node on the SceneTexture:PostProcess0 which treats the scene as is (with all lighting applied). Doing this will yield a result similar to the desaturation in Photoshop.
Ideally you would use the Desaturation node on the SceneTexture:PostProcess0 which treats the scene as is (with all lighting applied). Doing this will yield a result similar to the desaturation in Photoshop.