Windows is colour dumb (grrr)

It amazes me that Windows operating systems are still ignorant of colour management. Sure it allows me to define a colour profile and even make it the default, but then it does absolutely nothing with it.

The only software that gives me the right colours are those that are colour-profile aware. Why should they need to be ? Windows is supposed to be.

The result is that if I look at a photo in a web browser or word processor then I cannot trust the colours.

How difficult would it be for windows to adjust the LUT of the video card to match the default colour profile ? Pretty easy I would have thought. This is not ideal because the LUT may not have the same bit-depth as the profile, but it would be a good start, and the colour-profile aware programs could work around it if they knew the OS was going to do something with the LUT.

This has been a bit of a rant and I feel better for it, but if anyone can explain a way to make the screen colours look right when I'm not using DPP or PS, without ruining the profiled colours in DPP and PS, then I'd love to hear it.

cheers

Generally your calibration sw will activate the LUT on startup, so it does apply throughout windows, only the profile does not.

If you take care when profiling to shove as much as possible into the monitor and LUT (eg adjust RGB controls, assuming a CRT) rather than the profile, this can get web browsing quite close.

AFA the vast user world out there, things are an order of magnitude better than they used to be. Newer LCD's are actually reasonably close to sRGB out of the box. Not photo critical but certainly a lot closer and more consistent than the state of things 5 or 10 years ago.

- DL

Don Lashier said:

Generally your calibration sw will activate the LUT on startup, so it does apply throughout windows, only the profile does not.

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Dan, I don't understand this distinction you have made between the profile not being applied and the LUT being updated. Aren't they incompatible ? i.e. Doesn't modifying the LUT muck up the colours for the profile-aware software ? Or won't the profile-aware software reset the LUT before applying the profile ?

I've read about this stuff and got the impression that we could use profile aware software or an LUT updater, but not both. Maybe I need to do more reading but I'd appreciate it if you have the definitive answers.

Alan T. Price said:

Dan, I don't understand this distinction you have made between the profile not being applied and the LUT being updated. Aren't they incompatible ? i.e. Doesn't modifying the LUT muck up the colours for the profile-aware software ? Or won't the profile-aware software reset the LUT before applying the profile ?

I've read about this stuff and got the impression that we could use profile aware software or an LUT updater, but not both. Maybe I need to do more reading but I'd appreciate it if you have the definitive answers.

Click to expand...

Hi Alan,

My understanding is this:

The monitor is calibrated by adjusting the brightness, contrast and even the RGB gun levels in order to bring it as close to possible to the sRGB standard. Programs like Abode Gamma allow users to calibrate their monitors. Hardware monitor calibration devices also ask the user to do this, although with significantly more accuracy.

Once the calibration has been completed, a profile can be produced. For this, a hardware device is really essential. The devicee measures the actual colours displayed by the monitor for a given input RGB value. The monitor profiling software then applies the results of this profile to the graphic cards LUT, such that the monitor display sRGB as closely as possible.

Therefore, on a calibrated monitor, images in sRGB should be reasonably accurate regardless of the program displaying the image. With a calibrated and profiled montor, the colours should be even better.

Now, non-colour aware applications just throw the RGB information to the graphics card. Since the monitor is now adjusted to display sRGB correctly all is well as long as the colour space of the image is sRGB. If it isn't then the colours will be wrong. This is why viewing an Adobe RGB image using a web browser results in dull colours.

Colour manages applications will convert the image from the working space used to the monitor's working space as defined by the monitor profile. At this point I'm theorising, but I suppose the application then has a way of writing the newly calculated RGB values directly to the graphics card, overridding the LUT. If this wasn't the case then the application wouldn't need the monitor profile itself, but rather the generic sRGB profile. By using the monitor profile the application is able to display colours that are in the monitor's capability yet lie outside of sRGB. I hope that makes sense.

If someone more knowledgeable could confirm the last paragraph I'd really appreciate it.

Tim

Tim's basically got it right, except a profile aware app doesn't bypass the LUT - the profile is built on top of the LUT so the LUT is still in use.

As Tim pointed out, monitor profiling is normally a two step process - calibration thru adjustments, then profiling. With a good monitor it's possible to get quite close (to sRGB) with the calibration. The colorvision spyder sw will display the profile curves and I've managed to get mine nearly straight (diagonal) with careful calibration meaning that sRGB images in non-profile aware apps display nearly identical to PS.

- DL

Don Lashier said:

Tim's basically got it right, except a profile aware app doesn't bypass the LUT - the profile is built on top of the LUT so the LUT is still in use.

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I'm editing this post because I've since learnt lots of things! You're right.

I had assumed that when calibrating a monitor using a hardware device the LUT table was altered to produce sRGB output. This doesn't appear to be the case.

I now understand that the LUT allows modification of the monitor's gamma, but in now way it is used to change the resulting colour values in order to produce sRGB. Since most monitors naturally produce something close to sRGB, a calibrated monitor displays a good approximation to the sRGB standard when used with non colour managed applications.

If however you have a fantastic monitor that naturally produces something closer to Adobe RGB, then your sRGB images won't look correct in non-colour managed applications.

The resulting monitor profile characterises the calibrated monitor with the appropriate LUT that corrects for gamma.

Result: To get accurate colour, you need a calibrated and profiled monitor and a colour-managed application.

Tim

making sense, but...

OK guys we'd better stop soon because this is making sense whether or not it's right. As we probably know, my LCD screen has very little in the way of calibration controls other than brightness of the backlight, but that's ok. I've got it profiled properly too. I don't see much difference between prifiled images in adobe 1998 workspace in profile-aware software and sRGB images in non-proifiled software, so I guess I have the calibration and profile pretty well right.

However, what still confuses me is that windows needs to know what the default colour profile is, and the profile-aware software also wants me tell it what profile to use. It seems to me that windows is doing absolutely nothing with the default profile that it insists on knowing about. That gets me back to the thread topic - that windows is colour dumb.

Alan T. Price said:

However, what still confuses me is that windows needs to know what the default colour profile is, and the profile-aware software also wants me tell it what profile to use. It seems to me that windows is doing absolutely nothing with the default profile that it insists on knowing about. That gets me back to the thread topic - that windows is colour dumb.

Click to expand...

That's because windows does nothing with the default monitor profile other than tell other applications what it is.

Thus, in theory, you shouldn't be asked for your monitor profile - the application should find out by itself (which is the case for later versions of Photoshop, for example).