RGB values on main monitor appear to be out of whack

[purplehaze]

I am working on a late 2015 27" iMac monitor calibrated with a Datacolor SpyderElite5, struggling to match the color coming out of my Canon ImageProGraph-1000. I have not profiled the printer itself, but I am using the manufacturer's recommended paper profiles for my printer and the color differences are substantial enough to make me think something is off. I especially notice a lack of reds in the final prints and issues with blue. Yesterday I was doing a PS tutorial where the suggested foreground colour made up of RGB values of 48, 138, and 174 respectively was a dark teal-like colour on my screen, whereas it should have been a sky blue. (PS working space sRGB.) The same values input on my iPad gave me the blue I expected to see on my main monitor. When I switched from my calibrated profile to the default iMac profile in the ColorSync utility, the colour issue remained. I have restarted, recalibrated, checked lighting, done all of the usual troubleshooting, but nothing helps. I am running the latest version of Monterey.

Any suggestions?

[Manfred M]

Janis - I think every photographer who prints would like to get prints looking like what they see on their computer screen. Unfortunately, your computer screen uses an additive colour, transmitted light, RGB process, while the print uses a subtractive colour, reflected light, CMYK process. Your iPad does not support calibration and profiling, so the colours will not match what you see on your calibrated and profiled iMac screen.

You are likely running into a gamut issue where the paper you have chosen cannot reproduce the colours in the image. Saturated colours are often problematic in prints. In theory, your printer (depending on the medium you are working in) can handle a wider gamut (some colours into the ProPhoto RGB colour space), especially if you are working with a lustre paper (rather than a matte paper).

Being a reflected light process, you need to ensure that your print is well lit as well. Galleries blast light at them and generally exceed light levels of 250 lux. I usually evaluate my images at 150 lux, which is a pretty commonly used value for prints.

Which software are you using to print? If you set up soft-proofing, using the ICC profile for the paper you are using, will generally do a fairly good job emulating what your print will look like.

I hope that this all makes sense.

[DanK]

I don't use a Mac, so I'm mostly in the dark. However, those RGB values are a light sky blue on my sRGB monitor, not teal.

There is generally no reason to calibrate the printer, and the fact that you are clearly getting the wrong color on the screen suggests that the problem lies elsewhere.

I can think of only two possibilities. One is that for some reason, the calibration isn't sticking, but I don't know how Macs handle it. The other is that after 8 years, the monitor is failing--presumably the electronics, as a failure of the screen itself probably wouldn't be uniform.

If you know someone nearby who can lend you a screen, that would be the simplest way to tell whether the problem is the screen.

[purplehaze]

Thanks, Manfred, but I have come to believe that the issue is with the monitor's baseline reading of colour, as Dan appears to confirm. It may well be time for a new monitor.

[Manfred M]

Sometimes this is just a connection issue between the computer and the screen. Unfortunately, with the iMac, this is a real issue as there is no easy user fix (like changing a cable). That's one of the downsides of that particular, integrated design.

[billtils]

Janis

My money is on Dan's suggestion of age-related behaviour! I also agree with his suggestion to get your hands on another screen. Since you are a Mac user it may be an idea to see if you can get an iMac on a trial basis - it's a like for like move so will tell you whether or not it's your computer and if it is, you have the replacement all ready to go.

There is a pretty even spilt in the computer choices of my photo buddies with about half of us being happy Mac users and the other half being happy Windows folks. If it is indeed the iMac I would strongly recommend NOT to switch to Windows - there will be no observable difference in image quality but a lot of heartache getting used to a different OS.

[pnodrog]

I decided to check to see what colour to expect and came across an interesting site. https://www.colorhexa.com/308aae Doesn't solve your problem but maybe of general interest.

[DanK]

Thanks for posting. A nice tool. However, it requires that the monitor displays properly, so no help here…


Sent from my iPad using Tapatalk

[Round Tuit]

Hi Janet,
I don't know who told you that RGB values 48, 138, and 174 should render as sky blue. It is actually a shade of teal on both of my calibrated screens.

[DanK]

Odd. I'm finally back on my good calibrated monitor, and it's not teal on mine. I would characterize it as halfway between sky blue and baby blue. I would call teal something more like 38, 108, 108. But we can't show each other what we mean except via our monitors, so...

[Round Tuit]

I guess it means that the names we give to colours are not as standardized as we would like to think.

[pnodrog]

I guess it means that the names we give to colours are not as standardized as we would like to think.

If you google teal blue you will see about five different RGB values given. However the ratio of the RGB values given above is not to far off a lightish teal blue. If there was no red component it would be a blueish cyan. The red component merely desaturates the colour producing a lighter tint. Common usage of terms used to describe colours and their relationships are very poorly defined. Pantone is probably the most highly recognised reference to colours but cunningly/diplomatically give them numbers rather than names.

[DanK]

If you google teal blue you will see about five different RGB values given. However the ratio of the RGB values given above is not to far off a lightish teal blue. If there was no red component it would be a blueish cyan. The red component merely desaturates the colour producing a lighter tint. Common usage of terms used to describe colours and their relationships are very poorly defined. Pantone is probably the most highly recognised reference to colours but cunningly/diplomatically give them numbers rather than names.

Indeed. All that seems to be agreed is that it is a mixture of blue and green. Wikipedia gives 0, 128, 128.

I think the best way to resolve this, other than swapping monitors, would be this:

1. Take a photo of something uniform blue. Be sure to include a WB card to make sure the white balance is correct.
2. Examine the image on the screen. If it is greener, case closed.
3. To complete this, print it, and compare the print to the original and to the image on the screen. My guess is that the print will be close to the original but not to the image on the screen.

[Manfred M]

Look at basic colour theory to answer this question.

In RGB adding three different colour values is really going to result in a neutral gray (think ND filter) plus two RGB values

48, 138, and 174 can be viewed as having two separate components; (48, 48, 48) the ND component + (0, 90, 126) colour component. This means that there is a significant blue component (126) and a less significant green component (90) on top of a neutral base. Green + Blue = Cyan, so we have a sky that has a significant blue element and a somewhat lower cyan component. This all makes sense to me as skies typically are a mix of blue + cyan.