A common thread for all pixel access _get() functions is that you must provide an array with enough space to accommodate the data that you will receive. 

• Use IG_DIB_raster_size_get() to get the size of the array for storing a complete raster of an image.
• Use IG_DIB_pixel_array_size_get to get the size of the array for storing a specified number of pixels.
• Use IG_DIB_pixel_array_size_get to get the size of the array for storing a specified number of pixels from a single row, column, or line.
• Use IG_DIB_area_size_get to get the size of the array for storing a rectangular area of pixels.