retouching

So I have known for a while that the Blue channel is not particularly flattering on skin tones, and tends to show a lot of imperfections when retouching.

This can be used to our advantage by using the Blue channel as a 'guide' for seeing easily areas where some retouching/healing might be needed.

One of the secrets of great image manipulation is to separate images into components. Frequency separation is often mentioned, breaking the image into so-called high-pass and low-pass layers. The high-pass layer separates out the sudden changes in an image and fiddling with this layer can enhance sharpening or even out blemishes. The low-pass layer can be used for smoothing out color transitions. Portrait photographers use this extensively for smoothing skin and removing spots. There is no native Frequency separation tool or filter built into gimp.