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Photoshop 6

Colour Management

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By Ian Lyons

 

 

A Computer Darkroom Tutorial

 

When Photoshop 6 was announced to the world in late August 2000 much was made of features such as the improved interface, increased vector support, enhanced layer effects, etc. However, little was mentioned of colour management. Yet, the manner in which Photoshop now deals with colour within documents/images has been significantly altered, for the better.
 

This article will explain the main changes and make suggestions as to how the new Photoshop 6 colour management system should be configured. The reader shouldn't consider my preferences as "the best", just a base point from which to begin the process. However, careful reading should give some clues as to why I made certain choices.

 

Tutorial Index

To jump to a specific page simply click the underlined text

Pages 1 to 3    Introduction and Monitor calibration

Pages 4 to 5   Photoshop colour settings

Page 6           Colour Management Policies, Conversion Options and Advanced Settings

Pages 7 to 9   Soft Proofing and Printing

Page 10        Assign Profile, Convert to Profile and Saving Files.

 

Colour Management Primer

Typically each Device will reproduce colour differently, so that the colour we see at one stage of the imaging process will rarely if ever match the colour seen at the next stage. In other words, colour is Device-dependent. The purpose of a Colour Management System (CMS) is to maintain a consistent "appearance" of colour on different devices (i.e. scanners, monitors, printers, etc.) throughout our system. 

A colour managed system will comprise three basic components, namely: -

  • A device-independent colour space. Usually referred to as the Working Space or Reference Colour Space.
  • ICC/ColorSync profiles for each device (printer, scanner, monitor, digital camera, etc.) that describes the characteristics of the device.
  • A Colour Matching Module (CMM) that will interpret the information contained within device profiles and carries out their instructions on what way the colour gamut of each device should be treated.

A typical "Colour-managed Workflow" will involve the image data being passed along the chain - from scanner - to - computer - to - monitor - and printer (see the diagram below).  To minimise the colour discrepancies that result primarily from the widely differing colour spaces of each device we must give the CMM information in the form of device "Profiles" that accurately describe the colour gamut of each device. 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. I identify 3 companies who specialise in this business area later.

 

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It is also worth pointing out that whilst most low cost, consumer based film and flatbed scanner applications are ICC/ColorSync aware they tend to impose sRGB as the "Source" colour space. This colour space is  inappropriate for high quality image editing where print or film output is required. Some manufacturers e.g. Nikon, Polaroid and MicroTek allow us to scan and save our images in any Destination colour space we choose. Unfortunately others make similar claims but in reality the "Destination" colour space is generally always "sRGB". Furthermore, the image is rarely if ever delivered into Photoshop with an embedded profile (i.e. "tagged"). The new Assign Profile command introduced with Photoshop 6 will help overcome some of the problems this issue causes.

 

In with the New

Leaving aside (for the moment) the interface changes associated with configuring the Photoshop colour management system we find that the biggest and most far reaching change is; support for "document/image specific" colour. In Photoshop 5, it is the Working Space that defines how all the open images are displayed. Therefore, in order that we can preview the image accurately it must be in the same Working Space as is defined in the Photoshop 5 "RGB Setup" dialog.  However, with Photoshop 6, the Working Space defined in Color Settings only really has a bearing on three types of image, viz.: -

  1. new images/documents;

  2. existing images/documents without an embedded profile; and

  3. images/documents with no embedded ICC/ColorSync profile (i.e. "untagged images/documents" typically form digital cameras  and low end scanners, etc.).

"Image specific" colour means that it's the profile embedded within an image that determines how the image will be displayed and not the Photoshop Working Space. With Photoshop 6 we can have multiple images, each in its own unique Working Space open at the same time and each will be displayed accurately (of course this assumes a well calibrated and profiled monitor).

Another important change that users will quickly find is the absence of the "Display Using Monitor Compensation" checkbox. It's not that Adobe have removed the feature from Photoshop, but that they have configured it so that users can't easily turn it off, well not so as you find it easily, but I'll explain that workaround later.

Also note that a few new commands have been introduced, namely "Assign Profile", "Convert to Profile" and "Proof Setup". The first two are accessed from the "Image > Mode" menu, and the last from the "View Menu". I will discuss each of them in detail later.

I could go on at length waffling about each an every feature change, but I think it better that I leave such explanations to those who really understand Photoshop 6 colour management, namely Andrew Rodney and Chris Murphy.  Their material can be read at http://www.digitaldog.net and http://www.colorremedies.com respectively.

Please note that except for the obvious interface differences; Photoshop 6 for the Mac and PC share a virtually identical set of features. Therefore, the Mac OS based screen grabs shown below should be very useful to PC users. Of course there will always be those that look totally different, but so far as this article is concerned they are confined to printing and saving your images.

 

Part 1 - Monitor Calibration and Characterisation

On opening Photoshop 5 for the very first time users were provided with the "configure the colour management system" wizard, but such luxuries are not present in Photoshop 6. This means that the new user is already at a distinct disadvantage.

Nevertheless, we can make a start on our own by first calibrating and characterising the monitor. This can be achieved by using the now familiar Adobe Gamma utility.

Adobe Gamma is a "Control Panel" utility that can be accessed from the "Apple Menu > Control Panels" on the Mac and "My Computer > Control Panel" on the PC. Before running Adobe Gamma,
  • it is best that your monitor has been switched on for at least 30 minutes;
  • work in subdued lighting when calibrating a monitor using Adobe Gamma; and
  • set the white point of your monitor. Typically it will be set for 9300oK, which is far too blue for our purposes. 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.

Another good tip is to set your "Desktop Colour" to grey. Mac users can do this via the "Apple Menu > Control Panels" and then choosing  "Appearance". Windows users should choose "Start  > Settings > Control Panel" and then "Display".  Using Adobe Gamma is pretty straight forward, but I've included a few more tips along with the screen grabs.

Step 1

When the Adobe Gamma utility is first opened you will be asked to make a choice between the "Assistant" and the "Control Panel" method. It's probably easier to use the "Step by Step Assistant" method.

 

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Step 2

Choose your monitor profile or pick one that's close. If in doubt choose the Adobe default monitor profile or even sRGB, it really makes little difference since all we are doing is defining the start point.

 

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Before progressing to the next step, be sure to give the profile a unique description and include the date.

 

 

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