ImageGear for C and C++ on Linux v18.10 - Updated
Channels
User Guide > Concepts > Understanding Bitmap Images > Channels

An image is made up of one or more channels. For each pixel in the image, there are channel values for all of the image's channels. ImageGear supports the following channel types:

Each channel has a bit depth associated with it. This is the number of bits used to represent a value for the channel. This bit depth can be up to 32 bits on 32-bit platforms and up to 64 bits on 64-bit platforms. It is possible to have an image with multiple channels that differ in bit depth. For example, you could have an RGB image with 8 bits per color channel and a 1-bit alpha channel. Or you could have a 5-6-5 RGB image with 5 bits for red and blue channels and 6 bits for the green channel.

Previous versions of ImageGear stored alpha channels as separate, associated images. ImageGear now stores all channel values together for each pixel in an image.