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Ian Lyons

 

 

Now includes references to Photoshop 5.5 and Windows 2000!

Prior to the introduction of Photoshop 5 by Adobe, users of Microsoft Windows 95/98 had no real knowledge or experience of "Colour Management". Yes, most of us were familiar with the terms ICM and ICC, but in truth we saw very little evidence of its true power and functionality. On the other hand Mac users have had access to a system level colour management system for years in the form of "ColorSync". Even then many of the concepts and procedures introduced by Photoshop 5 have required a different approach from those of previous versions.
 

1. What's all the Fuss About

In truth, and for many, colour management is of no great importance, but for photographers and anyone else interested in the accurate reproduction of colour in print or on screen, it is one of the most vitally important features introduced by Adobe as part of Photoshop 5.

One of the most often raised issues relating to Photoshop is – "why don’t the printed colours match the colours displayed on screen?" Epson claim in one of their online support documents that the answer is quite simple - "because monitors and printers use different technologies to create colour". They go on to say - "no monitor will ever match the printed piece of ANY printer due to the fact that the human eye perceives colour completely different when looking at colour reflecting off paper or projection from colour monitors". However, this is only partially true, by ensuring that Photoshop is correctly configured it is possible to achieve "acceptably" accurate colour matched prints with only minimum effort.

This article explains the process of configuring the colour management system within Photoshop 5 for those aiming to optimise the RGB workflow required for making prints that come "acceptably" close to matching their on screen image when using inkjet printers from manufacturers such as Canon, Epson and Hewlett Packard.

Obviously, in the limited space available it is not possible to address all the issues pertaining to colour management. For those wishing to gain a better understanding of how colour management works within Photoshop 5 you should follow this link to Adobes On-line Guidance Documents:-

http://www.adobe.com/

Further information can also be obtained from Andrew Rodney's web site at:-

http://www.digitaldog.net/tips.html

 

The final section of this article deals with colour correction. Although not strictly speaking anything to do with colour management, I believe you will find it informative if not entertaining?

2. The Colour-managed Workflow

The purpose of a Colour Management System (CMS) is to maintain a consistent  "appearance" of any given colour on different devices (i.e.; scanners, monitors, printers, etc.) throughout our system. In order that we may achieve this it is first necessary for each device to provide the Photoshop Colour Matching Engine or Module (CMM) with some information on how colour behaves within that device, and this is provided through "Device Profiles".

A typical "Colour-managed Workflow" will involve image input via a scanner or Photo CD, being viewed on the monitor, with colour correction of images on the computer, and image output to a printer or film recorder. As the image data is passed along the chain - from scanner - to - computer - to - monitor - and printer, colour inaccuracies will be introduced. These inaccuracies result primarily from the widely differing colour spaces or gamut's of each device. To minimise these inaccuracies we must give the CMS information in the form of device "Profiles" that describe the colour gamut of each device. Using these profiles the CMS is provided with information that says for example,  "this RGB image data is from such and such a scanner, which sees colour in this way", the CMS will then know exactly what colour really looks like on that scanner. Likewise for our monitor or printer, again with suitable profiles the CMS will adjust the scanner image data into a form that the monitor or printer can show accurately.

Most devices are supplied with generic or "Canned" profiles that describe them pretty well, but for truly accurate colour matching you should seriously consider either getting "Customised" profiles for each device done professionally or buying your own profiling software (e.g. ColorVision Photo/OptiCAL, Praxisoft WiziWYG or Monaco Systems EZcolor).

 

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A Typical Colour Managed Workflow

It is also worth pointing out that whilst most low cost, consumer based film and flatbed scanner applications are ICC aware they tend to impose sRGB as the "Source" colour space. This colour space is not ideal for anybody seriously interested in obtaining high quality prints or film output from within Photoshop, in so far as its colour gamut is so limited. Some manufacturers i.e. Nikon, Polaroid and MicroTek allow us to scan and save our images in any "Target" colour space we choose. Unfortunately others make similar claims but in reality the "Source" colour space is generally always "sRGB". Furthermore, the image is rarely if ever "tagged" with a profile of any description, so the file contains no information relating to the profile upon which it is based.

 

3. Monitor Calibration

Having first installed Photoshop 5 on your computer the next task is to make sure your monitor is properly calibrated. If the  monitor is not correctly calibrated then we can have no confidence in the on screen colours being a true representation of the image data. Accurately calibrating your monitor is also an essential (if not critical) first step in developing a colour-managed workflow. For real accuracy we would normally wish to use a specialist hardware device, but these tend to be expensive. However, Adobe has provided us with an acceptable software solution for this purpose, namely "Adobe Gamma", although others are available see  (http://www.colorcal.com) for details.

The following information concerning monitor calibration is applicable only to Windows 98, Windows 98 Second Edition and Windows 2000. Users of Mac systems may find the procedure to be identical, but the dialogs will look slightly different.

"Adobe Gamma" can be accessed either through the Windows Control Panel Folder or via Photoshop's Help Menu and selecting "Colour Management". To be honest I don't like the Help version of accessing Adobe Gamma since part of the process involves overwriting ALL the hard work of RGB setup etc. (see later).

 

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"Adobe Gamma" is used to calibrate your monitor at "System Level" and thus ensures that unwanted colourcasts associated with your monitor are eliminated. The profile created as part of the calibration process becomes the "default profile" for your monitor and is also available for all other applications that can use ICC profiles. This new "Custom" profile is generally referred to as your "Monitor Space", and is unique to "YOUR" monitor. It is important to note that:- no matter what software application you are using, the image on screen is always being viewed in "Monitor Space".

A further point worth considering is your working environment. Calibrating a monitor during daytime and using it later in an artificially lit room is pointless, since your perception of colour in natural light is entirely different from that in artificial light. So consider carefully how, where and when you set up your system. A consistent environment is an essential prerequisite for accurate colour matching.

You should use a neutral background for the Windows desktop, and all screen savers and power management features should be turned off (and kept “off”). Allow at least 30 minutes after first switching on your monitor before commencing the calibration process. Set the white point of your monitor. This is a hardware adjustment, and how you do it depends on the monitor you are using. Most monitors have a control panel. If you're unsure how to set the white point on your monitor, consult the documentation that came with it.

Before we begin the process of calibrating the monitor check to see if "Adobe Gamma Loader.Exe" or a short cut to it is in your "Start Up" Folder.  The Windows 98/98SE Start Up folder is nested below the "windows/start menu/programs/startup" folder.

For Windows 2000 things are a little more complicated in that the "start up" folder is found deep down the tree in the "Documents and Settings" folder, and worse still each user has his/her own set of folders - you'll need to find it yourself!!! 

If after checking you can't find "Adobe gamma Loader.Exe" in the relevant folder; then you can make a "Shortcut" to the file, it is found in the "Program files/Common Files/Adobe/Calibration" folder (this assumes Windows based computer).

The following page outlines the various steps in calibrating your monitor based upon Adobe's recommended procedure and my own experience.

Step by step monitor calibration using Adobe Gamma

Step 1

On opening Adobe Gamma I recommend selecting the Step By Step or (Wizard) option. You should then follow the on screen instructions.

 

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Step 2

Adobe Gamma then tells us the profile upon which the subsequent calibration process will be performed.

 

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Adobe Gamma Profile selection dialog for Photoshop 5.5

 

Searching out a Profile specific to make and model of monitor is to a very large extent a waste of time, most are pretty awful, so if you don't have one don't panic.

Normally the first time you use "Adobe Gamma" the profile initially offered is the standard "Adobe Monitor Profile". We don’t have to accept this profile, we can actually select any monitor profile we want, but realistically it’s as good a starting point as any. In fact if you are using Adobe Photoshop V5.5 it is MOST DEFINITELY the place to start. Without going into unnecessary detail it is recognised that many manufacturer based monitor profiles are incompatible with the Photoshop 5.5 version of Adobe Gamma. In fact this is one of the reasons underlying some people finding it virtually impossible to get a good screen-to- print match. If you have a version of Photoshop prior to V5.5 then the problem with Adobe Gamma and manufacturer supplied profiles shouldn't be a problem.

Profiles locations:-

Windows 98 and 98 Second Edition - folder named windows/system/color

Windows 2000 - sub-folder named  system32/spool/drivers/color

Mac - ColorSync profiles are located in the System Folder/ColorSync Profiles folder

The dialog window shown above is unique to Photoshop 5.5 in that earlier versions don't have the "Description" window. This new window is actually quite important in that you can edit the monitor profile name. In fact I recommend that you do precisely that, otherwise the name shown will stay with the profile and cause you utter confusion next time open the Photoshop (e.g. - "Photoshop my profile says its sRGB, but I know it isn't"). Simply type the new name for your monitor profile and then select "Next".

If you have already calibrated your monitor using a manufacturer based ICM profile and would prefer to recalibrate using the above method then simply remove the old monitor profile from the relevant location as indicated below:-

The amount of adjustment required in the steps that follow will vary, depending upon how far your monitors’ actual behavior deviates from this initial profile.

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