Channel Modifier is a rule-based color channel modification plugin for Adobe Photoshop. It provides a host of mathematical operations which can be performed between color channels such as swap, copy, mix, addition, subtraction, multiplication, division, inversion, black and white.
Channel Modifier makes color channel swapping effortless.
Not only are red, green and blue channels available for manipulation but so are alphas.
Copy specific color channels from one channel to another easily and with immediate feedback.