Photoshop Proving Ground
Frequency Separation with Color and Luminosity Splits
Frequency separation (FS) is still one of the most important, powerful techniques for retouching currently available to photographers. The basic concept is to split high and low detail elements to more easily address things like blemishes and discoloration. In the September issue of Photoshop Proving Ground I add another layer of control.
Traditional FS stops at the detail level, but we can further split the low frequency elements into color and luminosity domains. The steps are a little different, but fortunately very easy to incorporate into current workflows, including automation through actions and panels. By separating color from luminosity, we have better control over each.
The dress on the right is a great demonstration of the power involved.
In the before image of the dress, you can clearly see wrinkles and staining. If we work only on the luminosity and leave the color behind, we can smooth out most wrinkles with a little blur and smudge. This adjusts only the gray values so any region that has consistent hue and saturation now looks more even as we smooth out the brightness variations.
But also look at the staining. The regions are both darker and have slight color shifting. Once we deal with the brightness variations, we can smooth over the color for consistency without changing the apparent depth or contours of the fabric. And of course the texture in the cloth is left untouched so long as we carefully choose the high frequency values.