Utility extracts pixels from .png images, allowing to use them in NuttX OS.
$ ./png2nuttx image.png
$ ls
image.png image-320x240.rgb ...
Utility makes use of LodePNG library from http://lodev.org/lodepng. Sources are included in the /lib folder. Don't need to do anything about that.
Pixels are being extracted from .png and saved into the file with the same name but with .bin added at the end. Format is absolutely raw, every 16 bits describes color of one pixel. No metadata at all.
Formats that can be exported using GIMP are all too complicated and BMP is a total mess. PNG is nice but the only interesting library I have found, called LodePNG, works with NuttX but doesn't support reading row by row. Without it, the limited amount of memory in microcontroller doesn't allow to process images larger than just a few rows.
If we have to convert from civilized format raw data is perfect.
In order to keep format simple, image dimensions are being saved in the file name image.png → image-320x240.rgb.
It can be easily parsed in NuttX with the following line
sscanf(strrchr(path, '-'), "-%dx%d.rgb", &width, &height);