Since we covered sharpening, lets quickly cover color balance / grading now.
Necessary theory before proceeding:
Lesson on color grading by Joanna Kustra
Parts of our photo are well saturated, but others aren’t. We don’t want to oversaturate pixels that are already well saturated, else our photo will look like a coloring book. Enter, selective saturation.
Selective saturation method 1 - Velvia module:
From the manual:
“The velvia module enhances image saturation. Its effect is tailored to increase saturation less on lower saturated pixels than on highly saturated pixels.”
“What it’s doing is changing the saturation (which is its intention), but at the same time it also changes the hue and brightness (which becomes awkward).”
Workaround attempt 1: blend mode chroma
“This blend mode mixes chroma (saturation) from the input and output images. Lightness and hue are taken unaltered from the input image.”
Workaround attempt 2: blend mode HSV color
“Only available with modules that work in the RGB color space; this blend mode mixes color from the input and output images, while lightness data are taken only from the input image. In contrast to blend mode “color” this mode does not involve clamping.”
“Velvia works in RGB”
So we have 3 variants of velvia (normal, blend mode chroma, blend mode HSV color) with different effects on hue and lightness.
Selective saturation method 2 - Color balance module:
Doesn’t have the same issues Velvia has. Great.
However, in its default state, it changes saturation globally, while we need to target only pixels that are below a certain level of saturation.
Which is why we need a parametric mask:
And an increase in saturation:
Match colors as per the color grading lesson.
1 instance of color balance: Give matching tints to shadows, mid-tones and highlights
Various instances of color balance:
Replace colors using the parametric mask to reach desired harmonies. You can target multiple channels with the same parametric mask instance for a fine-grained control of replacement.
Example (turn blue skies with a specific level of lightness into red):
Color control sliders -> RGBL
Turn on the parametric mask
Pick a certain hue / hue range to replace:
Pick a certain lightness level for that hue / hue range:
Pick the desired replacement color:
Adjust feathering to smoothen things out:
Enjoy your new sky:
In the same manner, with fine-grained control, you can color grade your photo. Enjoy!