彩度マスク (Saturation Masks)
動画：
A Quick and Easy Saturation Mask (InAffinity)
True 16 Bit Saturation Masks – Photoshop (Tony Kuyper)
参考：
Saturation Masks – a Simple Method (smadell) | Affinity Forum
Macro Updates for v1.7 (smadell) | Affinity Forum
Saturation Masks | Tony Kuyper Photography
Saturation Mask (dmstraker) | Affinity Forum
チュートリアル
How is Hue Calculated? (InAffinity)
Separating out Hue, Saturation and Luminosity Layers (InAffinity)