Thanks very much for both replies! Pixelarray looks like it will do exactly what I need at the moment.
Actually, I think I may have to recommend the .transform function. PyGame changes . . .
map_image = pygame.image.load('map_image.png').convert_alpha()
#pygame.transform.threshold(DestSurface,
Surface, color, threshold = (0,0,0,0), \
#diff_color = (0,0,0,0),
change_return = 1, Surface = None, inverse = False): return
num_threshold_pixels
What specifically are you trying to do to to map_image?