You can't just photoshop an image to make it pretty and call that science. NASA processes the image using calibration data taken from other sensors on the craft, trying to make as realistic a reconstruction as possible of the light data entering the camera, in a way that is physically reasonable and from which one can draw inferences from and not be accused of chasing image processing ghosts.
Except that many of the "pretty" images released by nasa to the media are only that. Scientific value is one type of value, promotional value another. That far out from the sun the only realistic pictures would be shades of black. Our eyesight isn't made for such environments. That they need to be photoshopped so that we can perceive their detail doesn't detract from the facts of those details. One image for us to understand and appreciate, another from which to make scientific measurements.
