Color depth (or bit depth) refers to the number of unique color values or shades (in grayscale images) available in a single pixel. The higher the bit depth, the more color information a pixel can store.
When creating a new project in Pixelmator Pro, you can choose whether you'll be working with a bit depth of 8 or 16 bits per channel. You can also change the color depth of an existing document in the Image menu at the top of the screen.
8 bits per channel, also known as "true color" lets you work with over 16 million different color values. As an example, the human eye can discern about 10 million different colors, so saving an image in 8 bits per channel is more than enough for quick enhancements, image compositions, and other basic edits. This doesn’t necessarily mean that 8-bit images are not as colorful visually, but it does mean that there can be much finer differences between shades of every color.
16 bits per channel, or "deep color", allow around 281 trillion different color values and is great for color-sensitive work. Editing in deep color gives you more color data to work with, so you can do some very specific color adjustments or corrections, and avoid image posterization (color banding).
Do one of the following:
Select 8 bits per channel or 16 bits per channel.