I am displaying data using function imagesc(). If I set fltk as graphics_toolkit image is displayed correctly.
Can't post images directly(low reputation) http://i.stack.imgur.com/ARiwF.png
If I use gnuplot as plotting program image is rendered upside down. fltk is unusable for me because its window isn't responding while function in octave is running. I also tried plot sine and it was correct plotted through fltk and gnuplot too.