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:

• IG_image_colorspace_get / IG_DIB_colorspace_get
• IG_util_colorspace_contains_alpha
• IG_util_colorspace_contains_extra

Here are some options for dealing with these channels: