You may occasionally want to work with only a portion of a bitmap or series of images. For example, when copying one file to another, if you had a 640x480, 30 frame FLC file, you might want to work with the lower right corner 160x100 portion, using every other frame, perhaps starting at frame 5 and ending at frame 15. The 'Custom' methods of the BitmapInfo class let you specify these options. Methods such as BitmapInfo::SetCustomWidth(), BitmapInfo::SetCustomX(), and BitmapInfo::SetCustomStep() let you specify the part of the source image that should be manipulated. The method that copied the image would see that these custom properties were set and would act accordingly. See theBitmapInfo class for details on these methods.

You may use the BitmapManager::ImageInputOptions() method to allow the user to specify these options via the standard 3ds Max Input Image Options dialog. This dialog simply sets the appropriate data members in BitmapInfo based on the user's choices.