I've drawn some sprites at 32x32 and they're great on the screen with transparencies (not with masks, but with ColorKeys in DirectDraw).

But now I've found that the sprite at 32x32 is little out of proportion for the other sizes of things in the screen. So I thought I'd simply change the destination RECT in the blit function from 32x32 to 24x24.

It still blits, but parts of the transparent colour (white) shows up around the edge of the sprite when it is blitted. What can I do to fix this?

I'd prefer not redrawing the sprite actually at 32x32, because there are simply too many to redraw, and I've tried it several times but I always ended up not having enough space to work with.