al_get_pixel - Man Page

#include <allegro5/allegro.h>

ALLEGRO_COLOR al_get_pixel(ALLEGRO_BITMAP *bitmap, int x, int y)

Get a pixel’s color value from the specified bitmap. This operation is slow on non-memory bitmaps. Consider locking the bitmap if you are going to use this function multiple times on the same bitmap.

ALLEGRO_COLOR(3), al_put_pixel(3), al_lock_bitmap(3)

al_lock_bitmap_blocked(3), al_put_pixel(3).