The depth of a layer determines how many levels of tone it can hold. For example, a 1 bit layer can hold to levels of tone - 0% and 100%. 8 bit layers can hold 255 levels of tone. The depth can be changed at any time to suit its needs. For example, your mask layers my be solid, 1 bit layers, but if you are ready to apply tones to these layers, you need to change them to 8 bit.
There are two ways to change the depth of a layer:
- Hold down ^ (control key) on the keyboard and click on the colour block in the Layers Palette and select a new depth.
- Activate the relevant layer(s) and go to Layer Menu > Change Depth.
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Note: If you are trying to apply tone to a layer and it is now working, it is likely to be because the layer is 1 bit in depth. If you change the layer to 8 bit depth and try to apply the tone again, it is likely to work.