-----Original Message----- From: Wayne Bretl <waynebretl@cox.net> Sent: Friday, July 05, 2019 1:23 PM To: 'Louis Dina' <lou@loudina.com> Subject: RE: Monitor Calibration Question I don't actually KNOW the answer, but it seems to me that having the monitor write to the graphics card LUT when you make a color temp adjustment ON THE MONITOR (not on some driver software) would not work, as the next time you boot up, the monitor profile would re-write the LUT. Also, if changing settings on the monitor actually rewrote the graphics card LUT, it would destroy the calibrated LUT until it was reloaded by bootup. [Unless the graphics card had two successive LUTS, one for the profile and one for the monitor hardware setting.] I believe LCD's must have internal LUTs, because their native transfer function is nothing like CRT gamma to begin with. So, this is an obvious place to make modifications for in-monitor color temperature settings, not back in the graphics card. Not knowing the number of bits precision in these various possible LUTs, I have generally assumed it's best to set the monitor to the preset for the color temperature I want (or the closest available) and then apply the colorimeter/spectrophotometer calibration/profile process to make minor changes in the graphics card LUT. Maybe someone who has thought this through more thoroughly can comment. -Wayne -----Original Message----- From: colorsync-users <colorsync-users-bounces+waynebretl=cox.net@lists.apple.com> On Behalf Of Louis Dina via colorsync-users Sent: Friday, July 05, 2019 8:51 AM To: colorsync-users@lists.apple.com Subject: Monitor Calibration Question I have a question about where the calibration adjustments are made in low to medium-end LCD monitors (not high end models, like Eizos). I have an aging Dell U3011 and a Viewsonic VP2365WB, which are 'okay' monitors, but certainly not what I'd call high end. With our old CRTs, we were able to adjust white luminance, black luminance, white point, etc, inside the CRT monitor itself using the monitor's controls. These preliminary adjustments did not alter the information in our video cards, leaving them in a pristine, straight-line condition. Then our profiling software made minor adjustments to give us a neutral grayscale with even steps between levels, and wrote this to the VLUT of the video card and to the vcgt tag in our profiles. Unless choosing Native White Point, this usually meant reducing the gain of one or two of the RGB channels. With consumer level LCDs, it was always my understanding that the ONLY analog control on the monitor was the brightness of the backlight (once again, I'm not talking about higher end LCDs). It was also my understanding, that if we altered the white point using the monitor's RGB gain controls, or selected a preset (such as 5000K, 6500K, 7500K, etc), these changes were reflected in the curves written to our video cards and not inside the monitor itself. I am questioning whether I am mistaken here. Do most consumer LCD monitors have the internal circuitry and graphic processors to make these changes independent of the video card in our computers? And if so, is it better to try to achieve our targets using the monitor controls? My approach to calibrating and profiling my monitors was to leave the LCD monitor's RGB gains all set to 100%, contrast set to factory default, adjust the backlight control to achieve my desired white luminance, then let the profiling software make all the necessary adjustments to achieve my targets for white point, white and black luminance, gamma, etc. Thanks for any feedback. Lou _______________________________________________ Do not post admin requests to the list. They will be ignored. colorsync-users mailing list (colorsync-users@lists.apple.com) Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/colorsync-users/waynebretl%40cox.net This email sent to waynebretl@cox.net