ImageGear for C and C++ on Windows v19.1 - Updated
Working with Alpha/Extra Channels
User Guide > Concepts > Migrating from ImageGear v14 > Working with Alpha/Extra Channels

When you access pixel data by using the pixel access functions in new mode, or directly via IG_image_DIB_raster_pntr_get, remember that alpha/extra channels may be present. These channels are stored along with the color channels on a per-pixel basis. You can easily detect their presence by calling the following functions:

Here are some options for dealing with these channels: