It turned out those were simple fixes (after finding the reason). The issue was that GMT accepts grids and images with several different memory layouts (row & column major, top-down or bottom-up, band-line-pixel interleaving) and you case was non consulting the original data layout. Those are now fixed and new versions released so please update both GMT and RemoteS
However, as I guessed above, your image is mostly all blacks. I suggest that you follow exactly that tutorial I mentioned above. Just replace the file names for your owns.
Your image
