Basic Colour Management: C1 & PS

In response to some other threads, I thought it appropriate to give a little guidance on the way you should set up a Windows machine for colour with Capture One and Photoshop.

First of all, you need to decide on a colour space you are going to work with (as a rule). I suggest one of three:

• AdobeRGB: my preferred everyday choice. This can handle a good range of colours and is ideally suited for printing - both offset litho and modern inkjets (which have driver options for AdobeRGB)

• ProPhoto: an astonishingly wide colour gamut. This can cover almost any colour you can see. However, because it is so wide you should always work in 16-bit per pixel mode, otherwise you risk posterisation. If you want to eek out every ounce of colour detail, or have absolutely precise adjustments in colour, then this is a great colour space.

• sRGB: if you don't want to get bogged down in colour stuff, then sRGB is the choice for you! It's the gamut that the web uses, as well as most high-street and internet printing services. It's pretty cramped colour wise, but generally it will do fine (but this one is last on my list when it comes to editing images!).

Calibrate your monitor
An absolutely essential step! Preferably you should use something like a Spyder/Huey etc which will physically measure your screen and produce a profile. Failing that there's the free WiziWYG from www.praxisoft.com - which is available for both Mac and PC (95,98,XP).

If you use WiziWYG, pick "Generic LCD" if you have an LCD monitor, and use D50 white point (but have very subdued lighting in the room), and 2.2 gamma.

Once your monitor is calibrated Windows will always display through that profile - you never need to reference the monitor profile again (it is used by the video driver, and once setup should always use it).

Setting up Capture One
Go into the colour management settings and set "Output destination (working space)" to your chosen colour space.
e.g. AdobeRGB

Never should this be your monitor profile or anything else. Capture One will translate the CCD information, using the "Camera Profile" you choose (e.g. Pentax istD generic v2) into that working space. This working space should be a standard - i.e. one of the three I listed above.

It's worth noting that you can try other "Camera Profiles" for your Pentax DSLR. Try any of the Nikon D100 profiles as they share the same sensor Capture One provides a "Portrait" profile that has much more muted colours. By changing the camera profile C1 is assuming the DSLR has a slightly different response - but still it will convert into the "Working space" - which should be AdobeRGB (or one of the others).

Setting up Photoshop
Go into the "Color Settings" dialog and, under "Working Spaces", set RGB to your chosen colour space.
e.g. AdobeRGB.

The "Conversion Options" can be set as follows:
Engine = Adobe (ACE)
Intent = Relative Colormetric
Use black point compression = checked
Use dither (8-bit/channel images) = checked

Under CS and CS2 there are "Soft Proof" options. For 99% of photographic work you should completely ignore this and not enable the Soft Proof! I'll can explain, but it's another huge chunk of info...

Saving for Web
If you are not using sRGB as your chosen colour space, then before you save for web you need to convert into the sRGB colour space.
Photoshop provides the option to do this under the Image menu (and annoyingly CS/CS2 puts it in a different place compared to PS7 and before).


I'll update this post with some more details later, but hopefully this should clear away some misunderstandings of colour!

Having set my *istD and PS CS2 to use AdobeRGB Colour Space, RawShooter reports that the monitor is using an sRGB profile. Does that matter, should it/can it be changed to AdobeRGB?

Matt,

Blueyonder email been down for a couple of days so I'll reply here.

I owe you a good night in the pub , although I'm having a bit of trouble calibrating my monitor with wiziwyg it's about as good as I'm going to get with my bare eyes (looks like I should invest in a Heuy).

The red tulips look pretty amazing now, no blown reds just the yellows and a bit on the fence posts clipping as you described.

Thanks a million.

Users of Photoshop can use Adobe Gamma, to be found in Control Panel, for monitor calibration.

For me, Adobe Gamma produces a better result than WiZiWyG.

I now have everything set to use AdobeRGB, time to play . . .

Peter,
Adobe Gamma does not handle LCD displays

To be honest, WiziWYG does a very good job - and that's comparing it to a Pantone Spyder 2 (which is better, but for general work, not by much). And how are you comparing it? You certainly can't go by the maxim that "my images look better when I use one" - you have to have a fixed reference, like a test chart, or calibration print.

It all comes down partly to how you set up the gamma - where you try and get the red, blue, and green matching the stripy background.
Best way is to use the Tab key to get the keyboard focus on the sliders, squint hard, and use the up/down arrows to get it matching.

And, yes, a hardware calibrater is often the best (though I've had some problems with certain LCDs). FWIW, www.ephotozineshop.com have a Huey in their mail-order returned section

Brian - glad to help

Matt

I wondered why my TFT Phospher wasn't listed

Sorry, I should have included a 'CRT only' reference in my previous post.

I bought one of those MO returned Huey's (thanks for the pointer) and it seems they have more if anybody is interested. £50 seems a reasonably good deal to me. I got an MO return (as new) Epson R800 for £170.00 too. I'm well happy as I've wanted (sorry, needed) one of those for ages.

I have had trouble with wiziwyg on my PC, it crashed as soon as I checked the monitor radio button, then hit next. Printer and scanner calibration seemed to work OK, at least as far as I would let it. Having messed about switching monitor profiles around from AdobeRGB to sRGB and a couple of reboots, it's working again.

You're right, squinting helps to get a much better result with Wiziwyg.

It turns our that I didn't buy one of those MO returned Huey's. It was apparantly sold 2 days ago and their website is not up to date.

Wiziwyg will have to do for now.

Thanks for this tutorial Matt!

However, I have tried WYZIWIG. A couple of problems;

1) I can't adjust the contrast using DVI connection 'twixt PC and LCD monitor.

2) Selecting D50 gives me a very brown colour where there should be grey. Is this purely down to my eyes not being very good at matching the squares and lines bit?!!

(Having set up some grey patches in PicWindowPro, these look brown)

Andy

Andy,
1) There's no contrast on DVI. Actually there's not even really a brightness, but a control of the backlight. (The Spyder2 Pro takes this into account). With DVI LCDs (as with laptops) you're generally ok with the brightness/backlight full on.

2) Make sure you set your LCD to factory defaults - especially the colour settings. Your LCD should have a "Normal" colour setting, or "sRGB" - use that.

In WiziWYG you should pick the "Generic LCD" type. Actually, when picking the gammas for each colour, you are better off with bad eyesight! You want to see it blurred so you can't see the lines around the outer edges. (In fact, it might be an idea to look through the camera with the focus off a bit)

Use the keys (not the mouse) for adjusting the sliders - it's much more accurate. If you can't tell where they are the same, then work out the upper and lower limits of where you can see the difference - then set the slider between those limits.

For checking - there's a few online references:
e.g. http://www.photobox.co.uk/popup.html?name=colourzoom

If you have Capture One (or the trial), there's a colour checker "PhaseOne-CMS checker.tif" in the installation directory. This is in the AdobeRGB colourspace

Matt

I have calibrated my TFT with Wiziwyg, but I use D65 as D50 gives very strange colour rendition. D65 seems better with my TFT.
My neighbour has a uncalibrated TFT. I made some pictures from their dog which I gave him. On his monitor they looked very pale, pictures from his own digital compact look quite ok on this screen.
So who is right...

I read a review somewhere recently that stated the Huey works great on high end lcd screens, but mixed results on more affordable units, causing the reviewer to give it a low rating as it is marketed towards people that are less likely to have high end monitors.

Golfdiesel - it depends.

If you get strange colour renditions when trying out D50, rather than D65 then you may either done something wrong, or the monitor is a bit odd. I have seen some cheaper LCDs that I can't even correct with a Spyder because they're so unstable colourwise. The Spyder2 has been better.

As with all things - you get what pay for (generally). Buying a cheapo second hand monitor and even running a Spyder2 on it is never going to make it perform like a £3000 Eizo If you have a cheap monitor and use a profiler on it (even WiziWYG), then it will be more accurate than the cheap monitor without profiling. But your images may not look "better" - perhaps because the monitor is straining to display the colour rendition.

The difference between D50 and D65 should mainly be brightness. Most LCDs in laptops can't get the 6500K temperature because they can't achieve the brightness needed for the whitepoint. Often D50 is more achievable. But it shouldn't be a great colour shift - D50 should appear slightly warmer than D65 too.

With any colour calibration you need a rock solid reference point - like a physical calibration print. You can never go on the premise that "images look good on this monitor" - because how do you know if both the monitor and the images are wrong?!

And don't forget that there are still differences between calibrated monitors - the colour gamut and brightness are usually different. Oh yes, and LCD backlights get dimmer as the unit gets older

Matt

So actually they way that the spyder2express handles TFT's isn't such a bad idea.
It only uses the native whitepoint of the TFT, allthough this is not what you want if you need to work on different screens with the same pictures.
I tried wiziwyg again with D50 and now I do see that the difference is brightness.
I am thinking of forking out the 90-100 Euro's for a Spyder2express or huey.

Colour profiles include three bits of info: gamma correction, phosphor numbers and white point.

Programs like Adobe Gamma and WiziWYG only load the display driver with a colour map that applies gamma correction. This allows applications which do not have built-in colour management to benefit from gamma-corrected image display. If you set up profile which has the correct rather than default phosphor numbers in it, apps like Photoshop and Picture Window Pro which have full colour management will also apply the phosphor and white point adjustments - and your images will look different in these apps than non-colour managed image viewers.

If your images look "more correct" in other viewers but are wrong in PS, then the chances are it is the phosphor numbers which are wrong, not the gamma correction. Note that Soft Proofing using the monitor profile in PS will display the image as per a non-colour managed application i.e. with gamma correction but without phosphor/whitepoint correction - this may explain why your image only looks correct when you soft-proof with the monitor profile.

I discovered all this while trying to profile my Sharp 172A, starting from the awful profile supplied by Sharp!

Hope you find this info useful.

One thing which may not be obvious is that assigning a default colour profile from the Colour Management page of the Display Properties does just about diddly squat. Assigning the default profile does nothing more than make it available to those apps which may want to use it.

When you run Adobe Gamma to create and save a profile, it makes an entry in the registry under

HKEY_LOCAL_MACHINESOFTWAREAdobeColorMonitor.

Run regedit and have a look. Run Adobe Gamma, create a few profiles with different filenames. Remember to Refresh the regedit display each time - you will see the Monitor Profile value change.

When you installed Adobe PS, it put a shortcut to Adobe Gamma Loader in your Startup folder (under your Documents and Settings). When you start Windows and login, the Adobe Gamma Loader looks at the registry setting, loads that profile and adjusts the display driver's colour map, replacing the standard sRGB colour map. So, all those apps which don't do any explicit colour managment themselves now uses the gamma adjusted colour map and therefore displays an adjusted image.

If you remove or change the default profile using the Colour Management page of Display Properties, this does not update the registry entry and Adobe Gamma Loader knows nothing about it. Hence, when you next restart/login, Adobe Gamma Loader ignores your change and loads the display driver with the profile indicated in the registry i.e. the last one saved through Adobe Gamma profiler. So if you are trying to compare different profiles, make sure you use Adobe Gamma to Load and resave. If you are trying to return to an uncalibrated state, either use Adobe Gamma to Load the standard sRGB profile, or move the shortcut to Adobe Gamma Loader out of the Startup folder; removing the profile from the Colour Management page will have no effect!

Things get a bit worse if you have tried both Adobe Gamma and WiziWYG - they both put their loader programs in the Startup folder and both try to update the display driver's colour map! I tried some deliberately awful profiles to make it obvious when the profile was being applied. I can see the desktop icons changing as each loader changes the driver's colour map at startup. Yikes. You should correct this by removing whichever loader is not required from your Startup folder.