On Sat, 2008-12-06 at 23:23 +0100, Peter Karp wrote: > Hi Leonard, > > > I still feel I am having difficulties because I don't understand hwo > > to use Brightness and Contrast in the monitor controls. > > For a TFT it's mostly easy. Reet the contrast setting to the default > value and never touch it again. This setting is totally nonsense and I > still wonder what the engineers/companies are thinking when they use > it on a flat screen display. Contrast setting on a CRT was a whole > different story (setting the gain). One thing that still puzzles me is just which of the 8 options I should choose when using dispcal -v -o ... I can use Brightness to set the white level (option 3, I think), but what about black level (option 1). I've been using various combinations of Contrast and Brightness to set options 1 and 3. Should I just ignore option 1? The default settings are Brightness 100, Contrast 75, but then when I shift to Custom mode, the Contrast level drops to something lower, 60, I believe. In any case, the default luminance level is (visually) much to high. I think I prefer something in the range 100-120 cd/m^2. > > Some better displays don't show you a contrast setting at all (Eizo, > Quato - when digitally connected). That's the best way. Others (for > example some NEC models) offer a contrast setting, but can be reset to > the default values pretty easy. Some displays offer a contrast setting > and it's not possible or unclear how to reset the complete OSD > settings or a specific one alone. This is the worst case. If possible > don't buy such a display. > > > Also, with the RGB monitor controls set at the default 50/100, I am > > getting lower color temperatures than I would prefer. I will > > experiment some more with the controls and also try setting the > > color temperature. > > I don't know your specific model, but in general it's a very good idea > to start from the default/factory values. > > 1) Don't touch contrast setting at all. (They use the monitor LUTs to > mimic a CRT behavior which does not make sense and will lead to > banding) -- so if available reset to the factory value. > > 2) Test if the brightness setting only influences the backlight -- > which it should. For this matter use some gray ramps and/or gradients > (non colormanaged is the best for this purpose). You should not loose > any levels, when altering the brightness. If it does, take care or > better buy a better display which does not connect the monitor LUT to > the brightness control. > > 3) If RGB default values leave headroom then test if increasing the > RGB values will lead to banding in R, G, B, Gray ramps. If it does not > you can use the complete range, if it does you have to reset the RGB > values to the default value and wire those default values as the > maximum _usable_ values to your brain ;-) > > 4) Use the brightness control to set desired luminance (or slightly > higher, because you will loose some luminance when you use the RGB > settings to reach the target whitepoint). > > 5) Then you can alter the color temperature (white point) with _two_ > of the RGB controls. Leave one of them -- depending on the choosen > whitepoint -- at the maximum _usable_ setting. As a hint you can > remember that lowering the green channel will also raise the measured > value for the other two channels (on most displays). > > 6) Recheck the luminance if needed/wanted. Important: the visual > appearance of the luminance (depending on the ambient light!) is much > more important then to reach a specific measured value. > > Alternativ route when you want to buy a new display: look for a > display which can be hardware-calibrated. For example used NEC 2180UX > go pretty cheap and can be calibrated under OS X and Windows with some > solutions. > > Hope this helps a bit. > > Regards > PEter > >