Image Depth, Bit Depth, & Deep Color Image Support
Bit depth is the amount of color information contained in each pixel in an image. An image with a bit depth of 1 means each pixel in the image can either be black or white, as the pixel can only contain 2 values (1 bit is either "on" or "off"). As the bit depth of an image increases, the colors each pixel can contain increases. New images in Acorn are created as 8 bit per component / 32 bit pixel images, which is suitable for most images used today. However, if you'd like to have a "deeper" image depth, navigate to the Image ▸ Image Depth menu item. You have the choice of selecting 8 or 16 bits per channel.
If you open up a 64 or 48 bit image in Acorn, Acorn will place your image into a 64 bit workflow and save the image in a 64 bit format.
If you open up a 96 or 128 bit image in Acorn, Acorn will place your image into a 128 bit workflow and save the image in a 128 bit format. For most cases, 128 bit depth is going to be overkill. If you want deep images, but don't know wether to go with 64 or 128 bit, go with 64. If you need 128, you'll know it.
Bit depth (as well as image resolution) also affects the size of an image. Images with higher bit depths tend to be larger in size than images with lower bit depths as the amount of information in the file pertaining color is greater.
Why would you want a higher bit depth?
- You have a camera that produces RAW files that are greater than 8 bits per channel. You may want to keep your image in that format to preserve fidelity for the future.
- Having a 64 or 128 bit image gives Acorn more breathing room to work on your image. Things like alpha pre-multiplication problems disappear and image adjustments are more precise.
- Scientific computing. Things like working with satellite or medical imagery can benefit from deeper colors. Just because the human eye can't see a difference between two colors doesn't mean it isn't there.
From left to right: 1 bit, 2 bit, 4 bit, 8 bit, and 32 bit images.
Images courtesy of Wikipedia
Deep Color Image Support
If you are running OS 10.11+ and have a 5k iMac or a recent Mac Pro with a 30 bit display then you can enjoy a new level of color accuracy in Acorn. When you create a 16bpc image you will enjoy deeper colors and a wider gamut.