- Local alpha is a per-pixel 256 step transparency, with 0 being transparent
- and 255 being solid. This is only available in 32 bit & 8 bit indexed
- colour modes.
+ Local alpha works differently depending on the colour mode. For 32bpp & 8
+ bit indexed, local alpha is a per-pixel 256 step transparency, with 0 being
+ transparent and 255 being solid. For the 16bpp modes 555 & 444, the unused
+ bit(s) act as a simple transparency switch, with 0 being solid & 1 being
+ fully transparent. There is no local alpha support for 16bit 565.