Let me add a little twist here.... so he wanted to restore the intensity and colors of the background. Just like shooting sunsets, most digital cameras well compensate for fading light and overexpose to bring white levels back up giving you an underdramatic and unrepresentative shot. Very often I will deal with this by underexposing the shot by a stop or two to bring the "drama" back to the sunset. In effect this is all this chap did. So, if he had dond this in camera by adjusting exposure (or correcting white balance), when it then still be as vile action? Does the "manipulation" have to be done post, or does in camera shooting exposure adjustments count too?
Quite simply...No.
The issue is with the manipulation of the image post-capture. Underexposure of the image by itself is not a manipulation, as it is not some form of digital darkroom trickery, but a function of the original capture process. The original image, even though it is underexposed, is still original and untouched. Once you begin making levels adjustments, cropping, resizing, etc....it becomes manipulation...because now you are altering the original image.




