Access RGB values from libraw_processed_image_t

I am developing an interface between javafx and libraw. Generally it is now working but only if I write directly to a TIFF or PPM file. I do not want writing first into a temp file and reading again from that file. Instat I want to use the memory image from libraw.

The problem actually I am facing with it is accessing the data from the call "libraw_dcraw_make_mem_image". From the documentation it should be an array of rgb pixels but all I am getting is one character back from an memorysegment.

Can someone point me to an example how to access the pixels of the memory image as RGB value which than I can use in the image class of javafx ?

Thank you in advance.