2 Replies Latest reply on Feb 4, 2008 12:22 PM by (Brian_Carlick)

    LCD's, when to change?

      I have had my LCD monitor (LG L1920P) for about 4 years. It is profiled regularly with an Eye-One Match. Looking at the profile graphs I have noticed that they have "bowed", I guess because of age? My question is how much "bowing" can be tolerated before "colour management" has trouble "correcting" the drift.

      Is this the time to change?

      Brian
        • 1. Re: LCD's, when to change?
          Brian,

          some thoughts:

          The calibration is OK if the target values are confirmed
          by the characterization. For instance:
          Luminance 80..100cd/m2
          Gamma 2.2
          Color temperature 6500K

          Somewhat 'bowed' LUT correction curves aren't harmful.
          A few levels are lost, but this is normally not observable
          in images.

          The LUT corrections can be forced to almost linear
          tone reproduction curves, if the monitor is adjusted by
          monitor menues so, that the LUT doesn't have to correct
          much. In other words, a pre-adjustment by trial and error
          so, that the monitor is almost correct without LUTs.

          Whether this is altogether better than a harsh correction
          by LUTs is doubtful. But the benefit is this: not color
          managed applications are shown reasonably.

          After finishing the Calibration and the Characterization,
          the result can be tested by patterns:

          Either the PDF, which requires correct settings:
          http://www.fho-emden.de/~hoffmann/caltutor270900.pdf

          Or the HTML doc which works with generic settings:
          http://www.fho-emden.de/~hoffmann/caltutor.html

          Best regards --Gernot Hoffmann
          • 2. Re: LCD's, when to change?
            Level 1
            Gernot

            Thanks for yr thoughts, the characterization confirm the target values luminance is ok at 90cd/m2, gamma 2.2, colour temp is 5500.

            But to get these values, I now have to set the gamma control on the monitor to -40, where as it used to be 0, the range is -40 to +40, the red channel is almost at max, the green and Blue at their mins almost.

            Hence my question about ageing.

            The screen itself looks ok colour wise, I will check it with yr patterns, but I have to make a trip to see my mother tomorrow, 85 and not well....

            On my return I will let you know the results of the pattern check

            Regds

            Brian