Photographers who are PC users, if you don't have a hardware based monitor calibration system like i1 or Spyder, Atrise Lutcurve is a good alternative. I just gave it a try on an out of calibration monitor. It's fiddly, and it took some time, but it worked. Monitor calibration is step one in photo colour management, and this tool might be the next best thing to hardware based calibration. One this is certain: with it being on sale for $12.50 today through this link, Atrise Lutcurve is a whale of a lot cheaper than the hardware approach.