ImageGear for C and C++ on Windows v19.9 - Updated
Option 1: Make your pixel access code aware of alpha/extra channels.
User Guide > Concepts > Migrating from ImageGear v14 > Working with Alpha/Extra Channels > Option 1: Make your pixel access code aware of alpha/extra channels.

If you want to work with alpha/extra channels in your pixel access code, this is the obvious choice. If you don't want to work with them but you want to be able to process images that may contain them, then you can calculate a per-pixel "stride" - the number of bytes between pixels - by using the channel depths, so that you can skip over alpha and extra channels, or you can use the next option.