[pygame] Color shift when blitting

[dejohnso <dejohnso@xxxxxxxxxxx>]

Hi,

I am loading a background map and blitting it to the screen. Once I have done this, I am getting color values under the mouse cursor.

However, I am seeing small color shifts between the image and the blitted image. For example,

from the screen with the background image: (103, 255, 103, 255) 
directly from the image: (102, 255, 102, 255)

This is also inconsistent. Sometimes, the colors are the same - even for the color shown above - so sometimes it gets shifted and sometimes not.

Does anyone know why this is happening? The inconsistency is particularly strange to me, as it implies the same start color is inconsistently blitted to the screen.

I am also seeing an overall color shift. The colors I am displaying from the screen or image are off by a few percent compared to the colors I see using a color picker in an image editing program.

The relevant code is

    map = pygame.image.load("AvoiderMap.png")
...
    while is_alive:
        # Check events by looping over the list of events
        for event in pygame.event.get():
  	….  

        screen.blit(map, map_rect)

        pos = pygame.mouse.get_pos()
        cursor_color = screen.get_at(pos)
        img_color = map.get_at(pos)
        print(cursor_color, img_color)

Thanks,
David