The short answer is yes your image can have more contrast and no this is not as good as your data gets. I did not work with your fit file, only your jpg just to show that there is more even in your final image. The proper way would be to start from the beginning though.
All I did was make a clone of your image. Then applied a star mask and reduced the smaller stars with MorphologicalTransformation. I then applied color to the stars and the background with the ColorSaturation tool. Next was the ExponentialTransformation and then the LocalHistogramEqualization tools for contrast. I them used The HistogramTransformation tool to bring the image background brightness closer to original image. I then blur this image with the Convolution tool. Now I'm ready to blend the 2 images together with PixelMath. The final step was make a star mask again and add some color back into the stars.
Like I said this would not be the way I like to go about this but it does show that this image can show a more contrast looking MilkyWay.
Mike
http://www.astrobin.com/users/msmythers/
