SPRITE LOADPNG [#]b, fname$ [,transparent] [,alphacut]
Loads SPRITE number b from the png file fname$. If no extension is specified .png will be automatically added to the filename. The file must be in RGBA8888 format which is the normal default. The optional parameter transparent (defaults to 0) specifies one of the colour codes (0-15) which will be allocated to pixels in the png file with an alpha value less than alphacut (defaults to 20). The variable transparency can then used with the command SPRITE SET TRANSPARENT n or FRAMEBUFFER LAYER n to display the sprite with the transparent region hidden.