Using the -b option to adjust the brightness of the output image increases the color saturation for any brightness > 1. This is particularly noticeable for large brightness values (e.g. 16) for which the colors start looking entirely unrealistic. A benchmark comparison can be done by doing the exposure adjustment in Photoshop (Camera Raw) or Lightroom instead. Is the underlying algorithm flawed or does the -b option need to get used in conjunction with some other setting ?