When working in Hue/Saturation (Layer>New Adjustment Layer>Hue/Saturation), it’s nice to be able to shift colors to whatever you like. Have you noticed, however, that you can’t add color to pure white or black, no matter how high you turn up the Saturation in the Properties panel? Even if you click on Colorize, those areas won’t take color. You may have noticed a Lightness slider in there. That’s not there to lighten or darken images; I mean, you can, but it looks bad. The reason that slider is there is to lighten black or darken white. When you move that magical slider, suddenly you can apply color to those areas, which previously seemed immovable. 

Excerpted from Colin Smith’s Photoshop Tips column, in the March, 2018 issue of Photoshop User magazine.