Converts RGB color image to L*a*b* color image, and vise versa.

All of SIC process are executed on L*a*b* color space, so first and last processing have to be executed by GKlab. a converted L*a*b* color image file have L* data in a R-channel, a* data in a G-channel, b* data in a B-channel. That why, a converted L*a*b* color image looks pinkish.

L*a*b* color space is similar to the color space that human visual system feels. The values of L*a*b* are as almost same as photoshop's L*a*b*, so you can use L*a*b* image created by Photoshop.