How to Expertly Color Grade Images by Mastering Luminance Masks
One of the most versatile and powerful secrets of Photoshop is the luminance mask. Similar to a channel mask that allows you to select very precise parts of your image based on color, the luminance mask allows you to select parts of your image based on tonal range. Using Photoshop to select those tonal ranges for you, you can quickly and effortlessly make very specific color and contrast adjustments to color grade like a pro.