png2c_ucg is a non-AVR program that converts a png image to h-file
with an array or if necessary to multiple arrays of pixels.
A inline static function which calls the array(s) can be used in
your AVR project.

To build the program:
  gcc -Wall -o png2c_ucg png2c_ucg.c -lpng

If library libpng is not available with MinGW/Msys2 use:
  pacman -S mingw64/mingw-w64-x86_64-libpng