Correct ICC and monitor mode setting

[magovec]

Hi,

a lot has been written about ICC and color profiles, but yet I still struggle to find the best setting. The element I have problem with is the monitor native color space simulation.

Assume I have an image, shot by a camera in sRGB. I have a monitor, calibrated, with its own ICC profile assigned to it in the OS. But the monitor has in its OSD menu several modes. It is wide gamut monitor, capable of aRGB. So if I open the mentioned image, has the ICC assigned and select sRGB in the OSD do I get a correct result?

Would I get the same result if I shot the picture in sRGB and select aRGB mode in the OSD menu of the monitor? (I think so as the monitor should know how to interpret colors and what will happen is that I will loose some colors as sRGB is a subset of aRGB. But loosing some colors is fine, I count with it, but expect to get the same grey/red/blue, etc. where the color was in the original image. Right/wrong?

Thanks

[Polar01]

Jiri if you are shooting jpegs the camera sets the colour space to sRGB as that is what all jpegs are save in. Now if you shoot in RAW it does not matter what colour space your camera is set to. Once you bring the file into a raw converter, say LR (LightRoom) or ACR (Adobe Camera Raw) a colour space is assigned. In LR it defaults to a form of ProPhoto RGB, in RAW you can assign sRGB, AdobeRGB, ProPhoto RGB or ColorMatch RGB. As you have a monitor that will show Adobe RGB, so if the colour space of the image is Adobe RGB than you should see those colours, if the image is sRGB colour space than you will see the colours still correctly.
You have not stated if you are running a custom profile on your monitor or are using the factory installed profile. If you use a Spyer or a Colormunki to calibrate your monitor than apply that profile and every time you turn the system on that custom profile will be applied to your monitor. Do not go into the system to pick and chose profiles, use the one you created. To do anything else is asking for trouble.
Hope this is of some help.

Cheers: Allan

[magovec]

Thanks for the info. This I understand. The issue I have is between ICC of the monitor assigned in the operating system (exactly as you described) and the settings I choose on the monitor itself (OSD menu).

You can have a correct calibrated ICC but if I set something wrong the image will look very differently. This is exactly what is happening to me. I have a right image with embedded profile (either sRGB or aRGB). I have a professional HW calibrated monitor with correct ICC assigned to it in the OS. And now I can choose several setting in the OSD of the monitor, e.g. color space, temperature, brightness, hue, gamma, etc. If I select "standard mode" it looks bright, full of colours. If I select "sRGB" it looks very differently. If I select Adobe RGB it looks very differently. All of which having displayed the same image and using the same ICC.

So I am confused what is the right approach. The monitor can be calibrated but the user setting affect the image the most. How can I know that for example sRGB mode is the correct one showing the colors as others will see on the sRGB screens?

This confuses me.

Probably it should be set to sRGB in case I plan to view the image on sRGB/web later on. I would not ask at all but what is very surprising to me is that in past years I was working with several panels, all of which were sRGB. I was used to some colors. Now when I see the sRGB colors on this wide gamut panel (Even set to sRGB mode) it is different. This might be either because the old panels were all cheap and crappy with anything but correct colors or I have something wrong

[ekki]

You should choose the mode that was chosen when the screen was calibrated.

Your monitor can show correct colours (more or less) in each of those modes, but you would need to have separate profiles for all of them.

[royphot]

Hi Jiri
Once you get your Monitor Calibrated and profiled, you should not make ANY alterations to the Monitor Controls. If you have made changes to the settings, you will probably need to have it re-done. I am rather surprised that whoever did the calibration and profiling did not tell you this.
Roy

[magovec]

Hmm, so I start to think that how the thing works here is that there is one ICC profile for the monitor as a piece of hardware, and because the monitor has some presets for several settings, the calibration was done for those presets, so if I select Adobe RGB I get the correct colors for Adobe space, etc. I have a report from calibration showing calibration values for sRGB and different for aRGB.

This would make sense to me. The only big surprise, which was the reason why I asked at the first place, is that the colors in sRGB mode are so different to my old monitor I was used to that it shocked me. But the old monitor was not calibrated at all so perhaps it showed very different colors then sRGB color space, which I thought it is more or less a color space it operates in.

[ekki]

magovec,
I think you should carefully read all the tutorials on color management posted on this website, they are really good:
https://www.cambridgeincolour.com/co...t-printing.htm

There is no one ICC profile for the monitor as a piece of hardware. The ICC profile describes the state of your monitor with certain setting applied to it. Usually when you hear about monitor calibration it means two things that happen at the same time:
1. monitor is calibrated
2. monitor is profiled and ICC profile is created

ad 1. Calibration = changing monitor setting to make it behave as you want it to. I don't know what model you exactly have, but lets say it has 3 predefined settings sRGB, Adobe RGB and Custom. When you choose sRGB you can also adjust brightness and contrast, but you can't control red, green and blue channels separately. Those are predefined by monitor manufacturer and they tried to set it up so the colour of the white is at it should be for sRGB (it is defined). The same story for Adobe RGB, both those colour spaces have some characteristics, and the manufacturer tried to make sure that monitor is adjusted to them.

In the custom mode you can adjust not only the brightness and contrast but also red green and blue, so you have more influence on how the screen behaves.

Those presets/adjustments obviously influence everything on the screen, because you change monitor settings. You might look at a black and white photo and notice that it is a bit too green, and it should be neutral, so you go into monitor settings and take some green away until it looks good, or you use some software that tells you what you should adjust.

ad. 2. Then you run some calibrating software, it sends different colours to the screen and using a colorimeter or spectrophotometer reads what the monitor is showing. So it sends 255,0,0 (RGB), which means the most saturated red, and it reads what kind of red your screen showed. It will show different red in sRGB setting and different one in Adobe RGB because the second one can display more saturated colours. It does not mean that Adobe RGB is better, but it has different characteristics, and sending 255,0,0 will result in different colour. It also sends something like 128,128,128 which should result in neutral grey, but it might have some colour cast (not every monitor is perfect). This software checks it and it knows if the colour was grey or not. It builds a profile of your monitor and this profile contains information about colours that your screen can show. But as I said, it will show different colours in different settings.

Sooooo
Lets say you profiled your screen both in sRGB and Adobe RGB mode, but you use it in Adobe RGB with Adobe RGB ICC profile (not a general AdobeRGB profile but profile created for your screen set to Adobe RGB) because you want to see as many colours as possible. You get an image with sRGB profile embedded, you open it in Photoshop. Photoshop reads both profiles (sRGB in the image and your monitor profile) and it compares the values. It knows that your monitor can show more saturated colours so it adjusts the colours that are sent to the monitor to make them look like they should. So it could convert the 255,0,0 from the picture to 240,0,0 and send this value to the screen.

Now if you had your monitor set up to Adobe RGB but you were using wrong profile, lets say sRGB, Photoshop would do the same, but the result would be wrong. It would read the embedded profile, it would read your monitor sRGB profile and it would also do the conversion. This time it would arrive at the conclusion that the screen behaves almost according to sRGB specification, so the values would be almost the same. It would send for example 253,0,0 and it would think you see the right colour. But you would see a colour that is much more saturated, because your monitor is set to Adobe RGB settings.

Sooooo
You need a profile that describes exactly how the monitor is set up.

Read those tutorials, seriously, they are written much better then my post ;-)

[royphot]

Calibration and Profiling are two different things. BUT Profiling is usually performed just after the Monitor has been Calibrated. Once the ICC Profile has been created using a Spyder or Munki or whatever, the instructions for that device are usually very specific about NOT changing ANY of the Monitor settings. That includes any OSD settings.

Please stop theorising and go and read the Instructions on the Profiling Colorimeter.

Roy

[ajohnw]

You should choose the mode that was chosen when the screen was calibrated.

Your monitor can show correct colours (more or less) in each of those modes, but you would need to have separate profiles for all of them.

That's it in nutshell. If you want to end up with sRGB images your display profile should be sRGB. If you want to end up with an aRGB image the display profile should be for adobe rgb. There would be no point in some one with an sRGB monitor having an aRGB profile. Some one who has an aRGB monitor should really have both and select the correct profile in the editor they use or on some select it at the system level.

People still post aRGB images on the web at times without seeming to realise that people who use purely sRGB monitors wont see them correctly as both sRGB and aRGB each contain colours that the other can't reproduce.

The information that you are working on in adobe products is kept in ProPhoto format so that none is lost as you adjust the image. In real terms it's just a deeper colour space. Another way of looking at that which less confusing is that it's 3x16 bit colour channels and they represent the accuracy level that the system retains while you work on it. Most cameras wont produce colour channels that deep. The next step in this direction seems to be 32bit floating point colour channels which is an HDR format. I doubt if any camera will ever need that much dynamic range even without the floating point aspect. The greater colour depths help prevent posterisation/banding effects while images are being manipulated into monitor colour spaces. Printers too after a fashion.

John
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[Polar01]

John just a note LightRoom defaults to ProPhoto RGB, when a raw file is brought in it, Photoshop CS to CC you set what you want the default to be, sRGB, Adobe RGB, ProPhoto RGB, and finally I believe it is ColorMatch RGB (it maybe other way around MatchColor RGB). It will stay in that colour space until you change it in Photoshop, not as you say "is kept in ProPhoto format".

Cheers: Allan

[ajohnw]

John just a note LightRoom defaults to ProPhoto RGB, when a raw file is brought in it, Photoshop CS to CC you set what you want the default to be, sRGB, Adobe RGB, ProPhoto RGB, and finally I believe it is ColorMatch RGB (it maybe other way around MatchColor RGB). It will stay in that colour space until you change it in Photoshop, not as you say "is kept in ProPhoto format".

Cheers: Allan

Adobe works much as I expected Alan. I have talked to other elsewhere about the difference between it and other packages. Adobe maintain a 16 bit workspace. That is the underlying data and doesn't relate to what appears on a monitor or a printer - other than a prophoto printer of course. We adjust images to look as we want them to though a profiled display or printer gamut. This link explains fairly well

http://www.luminous-landscape.com/pa...hoto-rgb.shtml

However it doesn't really clear up miss conceptions about aRGB and sRGB.

I was messed up on ProPhoto. I assumed it was a linear 3 x 16bit channel colour space but it turns out that it has a gamma of 1.8. Link of this page to the spec

http://en.wikipedia.org/wiki/ProPhoto_RGB_color_space

That page relates to trying to cover certain colour spaces with only 3 primary colours that cropped up recently. Prophoto needs imaginary colours which makes additive colour mixing as per displays a bit difficult. Probably possible with lasers. Bit difficult to print them as well as we can't see them. Same with pointer's gamut and only 3 primaries.

I do use one package that has the same sort of settings as Adobe. On that one for the reasons mentioned in the first link it's important to set the workspace to prophoto. The display profile is then set as required. I believe Adobe products should be used in the same way. Not that I am ever likely to use one.

There is something about this on Adobe's web site some where. My impression from that was that things underneath are handled 3x16bit linear and then profiled at the actual output as required. On the other hand this may have been on an ICC page or some organisation like that. Neither had the information that I was looking for concerning raw conversion and colour space outputs. There are indications that a straight raw to 16bit format is used and then tone mapped to what ever. As raw is 12 or 14 bit in most cameras this leaves max room for manipulation but produces rather dark images as it comes but is as raw as raw can be. Frankly I wouldn't rule out packages calling this prophoto as profiling with a gamma unless it's needed doesn't make much sense to me.

John
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