There is a long sad story that goes with this debate. Several years ago when astrophotography was starting to catch on in amateur circles there was a vigorous debate about whether pictures should reflect reality of the science or be interpreted solely for their beauty. The science side held the moral high ground but over time were swamped by events in the market place. The software vendors have no sympathy with scienctific realism and they install auto whitebalance routines all along the chain of processing. Starting with antiblooming gain on the chip and the color masks of popular DSLR cameras through the conversion to JPEG and into the world of photoshop. It is extremely difficult to get an accurate color balance with amateur equiptment. When it is achieved with much effort and special equiptment the results are less "pretty" than most people want to see. For the science, we know the color of M22 by brute force analysis of individual stars. lots of them. There are no vast populations of blue stars in the cluster. http://www.slas.us/gallery2/main.php?g2_itemId=2033 We know where the mainsequence cutoff is, it is redish, and you can see the spinkle of blue stragglers to the left of that. This is the reality of M22, the science. DT