When running a multi-headed setup on a budget its not always possible to have identical monitors; this introduces the really irritating problem that across your screens the colours dont match. If like me you spent hours and hours playing with colour controls and pieces of software which supposedly help you set your gamma, etc and still never quite managed to get it right - then you probably need to invest in a colour profiling tool.

At first I thought such devices were perhaps a little over the top, being reserved for the realms of professional publishers and photographers, etc. but after investing in one myself I can honestly say it was well worth it. Now not only can I upgrade individual monitors whenever I like without upsetting the balance of my system but I can be rest assured that what I see on my screen whilst doing web design or processing images, etc. is as correct as it can be.

What is colour management?

Colour management is actually quite a complicated subject, certainly too much to cover fully in this blog. But put basically; in the same way that the sound from your HiFi system never truly matches the sound of the original music, your monitor and printer (and for input: your camera and scanner) never truly match the original source image. You might think its by a small amount but you're eyes and brain are actually quite good at correcting images which are quite wrong, sometimes its only when you have two monitors sat next to each other with the same image on them you realise how massively different the two displays are ...hence the purpose of this blog.

To get the right colour management settings you use a device called a colour profiler. This is basically a calibrated piece of hardware which looks at the colours given by your device and in conjunction with its software makes a map of how much you need to change each colour to make it match a standard. These changes are called a colour profile and you will need one for each device you wish to be accurate (monitor, printer, scanner, camera, etc). Its basically analogous to the settings you might use on your HiFi graphic equaliser to make it sound as close to the original music as possible.

Whats out there?

I don't intend to go into massive detail about the products available here, as to be honest I don't have the facilities to test or make accurate recommendations but suffice to say there are two popular colour profiling products on the market you should check out. The GretagMacbeth range by Xrite and the ColorVision range by DataColor. Out of the two ranges I found the ColorVision Spyder2Pro and the GretagMacbeth Eye-One Display 2 (sometimes called i1Display 2) to be the most suitable products for my application as they are the current models which support multiple monitors and do everything you need to match your screens.

After much blog reading, looking at specifications and checking out the supplied software I decided on GretagMacbeths product which I purchased from WarehouseExpress. This was actually contrary to my initial instincts to go for the Spyder product (on the basis that it was much cooler looking) but I'm glad I did choose the Gretag because the Gretags superior software more than makes up for its dullness.

The feature I like in particular on GretagMacbeths software is that it gives realtime colour information which guides you to adjust your monitor using the monitors built in colour controls before it scans and creates the profile. This gives you the best chance of getting everything as right as possible before the colours are corrected using brute force methods such as the graphics card LUT. (The Spyder software may have this facility now but when I was looking to buy it didn't.)

Installation and use

The GretagMacbeth is extremely easy to install and use even with multiple monitors. Once you have run through the setup and launched the calibration application, simply drag it to the screen you wish to calibrate, run through the wizard and save the profile; giving each of your displays an individual file name. It should be noted that on XP you can only have one colour profile on each graphics card; so if you have two different monitors on the same card you need Vista or another graphics card. To my knowledge this is a limitation of the XP OS not GretagsMacbeths software.

Problems with LUT loading...

OK now to the main purpose of this blog. GretagMacbeths software like all good monitor calibration software comes with a LUT loader, in the case of the Eye-One Display 2 its in the startup folder and called the "Logo Calibration Loader". What this does is load a Look Up Table (hence LUT) into your graphics card which tells the graphics card how to display each colour properly. Now lots of people appear to have problems with this working so I thought I'd explain how to solve a few of them.

The problems themselves are not actually with GretagMacbeths loader but with loaders from other software which also load LUT's onto your graphics card, hence destroying all the good work you have done... Heres a few of the common culprits.

Adobe Gamma

During the Adobe Photoshop installation it installs a gamma loader which uploads a LUT to your graphics card based on a 'by eye' test which is available inside the application itself or control panel. To disable the loader you need to go into your startup folder and remove the "Adobe Gamma Loader" otherwise basically this application will override any settings you have done with your colour profiler.

Paint Shop Pro

Paint Shop Pro is a real pain as it appears to have a bug whereby it loads the LUT table stored in the configured colour profile onto ALL graphics cards instead of just the graphics card connected to the monitor which you have associated the particular colour profile to. This sets basically sets all the LUT's the same across all monitors which of course you don't want as all your monitors aren't the same. It seems to be a problem in both Paint Shop Pro X and Paint Shop Pro XI. I reported this to Corel via email this time last year but the support tech just replied with the usual "upgrade your graphics drivers" email which was of course completely unhelpful.

To solve the problem I have disabled colour management in Paint Shop Pro, not an ideal solution but at least my displays don't get screwed up.

If anyone knows if this is fixed in Paint Shop Pro X2 please let me know, as without getting into a huge debate Paint Shop Pro is definitely my personal graphics package of choice over Adobe Photoshop.

NVidia themselves

I have to admit this one caught me out. My machine booted fine, all looked good then *bink*, all the colours where wrong again. After playing around with msconfig (a really useful built in utility which allows you to disable various startup applications, just click start->run and type msconfig) I discovered that the cuplrit was a bunch of DLL's which start on bootup written by nVidia.

If you look inside:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run

...depending on your system you might see these 3 entires: NvSvc, NvMediaCenter and NvCplDaemon.

Now the one which caused all the problems for me was NvCplDaemon so I made a backup copy of the registry values and simply deleted it. This solved my problem completely and I have had no detrimental effects as a result. Its my guess this simply loads up the settings you have stored on the nVidia Control Panel but since I'm not using those settings its not a problem to disable it.

Summary

To summarise colour management is tricky at the best of times and in fact I've barely scratched the surface here skipping over crucial steps such as configuring colour profiles in applications etc. However personally I found the results surprisingly worthwhile and well worth the effort, even if its just for the fact that now all my monitors look identical.

Posted by Daniel: 12:34, Wed 5th Dec 2007