Custom UI on S3A7 LCD

I am trying to create graphics display on S3A7 Fast prototype kit which has LCD display. This panel don't support jpeg or any other compression format, only supports terminal kind of text display.

But driver function support paint the screen by loading 16it pixel map data to display any graphics we need.

My question is how to create these pixel map data for my own design.  As we can use GUIX tool to design your own UX display and use that on SKG2 board which supports jpeg decoder.

There are sample application for S3A7 board which display graphics text but how to generate these pixel map data ?

Thanks

MK