The following code loads a picture which supposedly has transparent background. However, the gray/white tiles are still visible on the screen.

screen = pygame.display.set_mode((800, 600))
background = pygame.image.load('background.png').convert_alpha()

player = pygame.image.load('player.png').convert_alpha()
player_rect = player.get_rect()
player_rect.topleft = (100, 100)

How can I remove the background so that only the characters are shown?

I tried with convert_alpha() command but it didn’t have any effect.