Why does Surface.convert() lose transparency?

convert() matches the display surface format, which usually has no per-pixel alpha (just colorkey). Use convert_alpha() to preserve per-pixel alpha. PNG transparency works only with convert_alpha.

convert vs convert_alpha performance?

convert is fastest; convert_alpha slightly slower because it preserves alpha. Both are required compared to no convert. Use convert for opaque, convert_alpha for translucent.

set_colorkey alternative?

set_colorkey makes a single color transparent. Use after convert when you have a magenta-key sprite. Faster than alpha but no smooth edges.

Fix: Pygame Surface.convert Drops Alpha

Quick answer: Use image.convert_alpha(), not image.convert(). Per-pixel alpha preserved.

PNG with translucent edges. load(...).convert(). Edges become opaque squares. convert() drops alpha.

The Fix

# Drops alpha
# img = pygame.image.load("sprite.png").convert()

# Preserves per-pixel alpha
img = pygame.image.load("sprite.png").convert_alpha()
screen.blit(img, (10, 10))   # translucent edges blend correctly

convert_alpha is the canonical fix. For opaque sprites, convert is faster; pick by content.

Verifying

PNG with soft edges: smooth blend with background. With convert(): hard edges, magenta-style square.

“convert_alpha for translucent. convert for opaque.”

Related Issues

For collide_mask, see collide_mask. For PyInstaller, see PyInstaller.

convert_alpha. Edges blend.