DisplayCAL - previously named dispcalGui - is an open source software system that is the GUI for the Argyll Color Management System, useful for calibration of computer displays (and other purposes probably). http://displaycal.net I have a Spyder5 Express display calibrator. It is an inexpensive system that includes a colorimeter sensor box that connects by USB, and it comes with its own software that works pretty well to do a fast calibration that improves the colors and match between my monitors. However I want to see if I can do an even better calibration using DisplayCAL. I tried a calibration with DisplayCAL last night and I got results that were not as good as obtained with the Spyder5 Express software. I got an error message when the software tried to get a colorimeter correction file for the Spyder5. DisplayCAL asks for a password, I think this might be something to do with "sudos" or system security, I am running as a standard user (not an admin) and maybe that is the culprit. Normally when I install or use certain software I can just input my admin name/password but that is not happening. DisplayCAL was able to proceed and do a calibration without the colorimeter correction data. However the resulting display profile produced questionable results, there is significant "black crush" in displayed images. Here is a review of the Spyder5 that suggests the user could pair the Express version with DisplayCAL to obtain an excellent low-cost calibrator system with capability equalling higher-end systems: http://cameratico.com/articles/datacolor-spyder-5-review/ Any help is appreciated!