- This topic has 4 replies, 4 voices, and was last updated 2 years, 6 months ago by
.
-
Posts
-
Hey guys, i am a colorist but not too technical in terms of calibrations. Said that to say I have a good eye for colour.
Right now due to covid situation I am working from home, I got myself a benq sw2700 and a lg 27gl850 monitors. Calibrated them close enough as well.
The behaviour i see is that as soon as I switch on the monitors, the benq seems to be a lot greener and lg seems to be a lot reddish. And it takes about 30 mins I guess after which they look similar to how i calibrated and match closely enough.
Is this normal behaviour of screens? I know there is some variance and hence we let them warm up before calibrating. But is the difference of warming up so visible? Should I replace these monitors?
I don’t know because the screens in my office are calibrated by some other team and they are almost always on. And hence never came across such behaviour
Yes it is common for there to be subtle change in brightness and color temp as a screen warms up. This is why it is recommended to have the screen on at least 30 minutes before doing your calibration/profiling. Same is also true for the measuring device. It’s best to place it on the screen for some time before you do any measurements so it can warm up as well. One thing I do is start the manual adjustment step and leave it there reading the screen for 10 minutes or so before doing my adjustments and moving on to the rest of the calibration.
I don’t notice newer screens with LED backlights doing this as much as screen with CCFL tubes did but i’m sure they still do.
Also since many backlight technologies are dependent on phosphors those do degrade over time with use which will result in a shift of the color balance as the screen ages. Which is why for color critical work it’s recommended to recalibrate/profile like once a month
Your panels have little difference in green spectrum, I’m not sure that this can produce metamerism effect. The first question is how much time come over since the last calibration? Panels have different aging. By example, I’d recalibrated iMac 27″ yr. 2017 mfg. after 1 yeasr and 1 month and it had acceptable color error for consumer grade photography, but other high quality panels my loose precision after one month of daily work. Eizo recommends to recalibrate display once in two weeks, but they’re perfectionists and modern CG monitors have integrated colorimeters. All in all if this time is more than two months for colour-critical tasks and 4-6 months for others, I recommend you to do test. Note that DisplayCAL ccss database usually contains non-verified CCSS corrections (sometimes made for non-native gamut and non-typical lightning modes) made by ColorMunki devices, that are non precise themselves. If you use the same ColorMunki to build correction for both displays, you’ll have the same bias, but you don’t know database devices ID. Better to rent i1Pro / Pro 2 / Pro 3 to build correct CCSS and personal CCMX for your colorimeter.
Beware of panel non-uniformity. Fill in your screens with light grey and dark grey, check them visually from 2-3 meters and from side positions. There’s uniformity test in reports menu of DisplayCAL, however visual control may be enough here and measurement devices are too big to catch some defects. You may also “palp” screen in pre-calibration stage, when DisplayCAL shows RGB bars and color bias. Hue error is much more valuable than lightness decrease. Choose some compromise point near center of the screen if your panel is not perfect.
Beware of the same profile type for both displays, monitor settings (full gamut, WP native or tuned to real 6500K or whatever you use, gamma level) and white and black levels. These should be close enough, though it’s difficult to get close blacks if they aren’t close “from the box”.
