640*480 is a bad texture size, use power-of-2 sizes: 32,64,128,512,1024 etc.
So you could externally resize your Sprite Texture to 512*512 and then scale the sprite in Blitz to fit the screen. I don't know, maybe that's the reason why you've got that garbage onscreen.
So you could externally resize your Sprite Texture to 512*512 and then scale the sprite in Blitz to fit the screen. I don't know, maybe that's the reason why you've got that garbage onscreen.