Home > Articles > Design > Adobe Photoshop

Color Settings in Adobe Photoshop CS4

Jan 8, 2009

📄 Contents

␡

⎙ Print

< Back Page 5 of 10 Next >

This chapter is from the book 

Real World Adobe Photoshop CS4 for Photographers

Learn More Buy

Photoshop and Your Monitor

Photoshop displays everything through your monitor profile. If your monitor profile doesn't accurately describe the actual behavior of your monitor, your judgments about your images won't be accurate, which means your corrections will also be inaccurate. We're guessing that's not what you want.

Photoshop uses the monitor's profile to transform color data on the fly as it gets sent to the video card so that the monitor displays the color correctly. The great benefit of this approach is that it makes it possible for people using very different monitors on different platforms to view the same image as consistently as possible. This makes monitor calibration a mission-critical necessity! (The only time this behavior doesn't happen is if you set the working space to Monitor RGB, which we don't recommend.)

To make this magic happen for you, you need an accurate profile for each monitor. To display color accurately, Photoshop needs to know how your monitor behaves—what color white it produces, what sort of tonal response it has, and what actual colors it produces when it's fed pure R, G, or B. Photoshop gets this information from the display profile. Although a default display profile is assigned to your monitor by your operating system, you'll get the best results from a profile customized for your specific monitor.

Color Settings and the Color Picker

Why are we talking about the Color Picker in this chapter? Simply put, a great many people overlook the fact that the Color Picker is subject to the choices you make in Color Settings, because the numbers that appear in the Color Picker for all the color modes other than the current document's mode are the product of color-space conversions made using the default profiles, engine, and rendering intent.

We've lost count of the number of e-mails we've received from confused users who tried to specify black as 0C 0M 0Y 100K in an RGB document and then got bent out of shape because:

The resulting color was dark gray.
It picked up a bunch of C, M, and Y on conversion to CMYK.

Well, 100K isn't black, because black ink isn't perfectly black or perfectly opaque—if it were, we'd never need to lay down more than 100 percent total ink. If you specify 0C 0M 0Y 100K in the Color Picker and then look at the RGB values, or at the Lightness value in Lab, you'll find that they aren't zero. And unless your CMYK working space uses maximum GCR, 0C 0M 0Y 100K isn't a "legal" value for a converted RGB 000 black—you'll almost always want to add some amount of CMY to increase the density.

The Color Picker is governed by two simple rules:

The "real" color being specified is represented by the numbers relevant to the color mode of the current document, which may not be the numbers you're entering. If you enter CMYK numbers while working on an RGB document, the color you're actually specifying will be represented by the numbers that appear in the RGB fields, and vice versa.
When you specify color in a mode other than the document's, the actual color is calculated by taking the color values you entered and converting them to the document's mode using the working space profile for the mode you specified as the source profile, the document's profile as the destination profile, and the rendering intent specified in Color Settings.

When you think about it, it's hard to imagine how this could work any other way, but how may of us think that way in the Color Picker?

You also have to maintain your monitor profile. Monitors drift over time, and though LCDs tend to drift much more slowly than CRTs, a profile that was accurate when it was created may not be accurate a week or a month later. Professionals whose jobs depend on accurate color may decide to update their monitor profile every week or two; some people go for a month or more before updating the profile.

There are two distinct ways to compensate for monitor drift.

You can adjust the monitor hardware itself to bring its behavior into agreement with a specific standard, a process called calibration.
You can create a profile that describes the behavior of the monitor, a process technically known as profiling or characterization. A profile basically describes the difference between the standard and what the hardware can actually achieve, so that the color management system can make up the difference when sending the image to the video card.

In practice, most monitor profiling tools do both, and they make no clear distinction between the two. (This is why many people refer to the entire process as "calibrating your monitor," even though that's really only the first part of the process.) The practical distinction boils down to the aim points you choose, and how much of each you end up doing depends on the adjustments offered by the monitor.

Calibration Parameters

Monitor profiling packages typically ask for the following parameters:

White luminance: The brightness of pure white on the monitor, specified in candelas per square meter (cd/m²), or foot-lamberts.
White point: The color of the monitor's white, specified either in Kelvins or as a daylight temperature such as D50 or D65 (see the sidebar "How White Are Your Whites?" later in this chapter). For practical monitor calibration purposes, you can treat 5000 K and D50, or 6500 K and D65, as interchangeable.
The tone response curve, usually specified as a gamma value.

Some packages also let you set a separate black luminance value, but only for CRT displays. LCD displays have a fixed contrast ratio, so the black luminance depends entirely on the white luminance.

Creating a Consistent Viewing Environment

Three factors combine to produce the sensation we describe as color: the object, the light source that illuminates that object, and the observer. You are the observer, and your color vision is subject to subtle changes brought on by everything from your diet to your level of sleep. The other factors that affect your color vision are, fortunately, easier to control:

Lighting. Consistent lighting is vital if you want to create a calibrated system. In the United States, color transparencies and print proofs are almost always evaluated using light with a controlled color temperature of 5000 K. In Europe and Asia, 6500 K is the standard—it's a little more blue.

You need a consistent lighting environment for viewing your prints; otherwise the light falling on the print you're evaluating will constantly change. You can brick up all the windows in the room and install D50 lighting everywhere, but for most of us that's impractical. An easier way is to orient your monitor away from direct window light, turn off the standard room lights for color-critical evaluations, and instead use a relatively inexpensive 4700 K Solux desk lamp for evaluating photographs and prints.

Theoretically, the ideal working environment is one that has low ambient light (almost dark). This maximizes the apparent dynamic range of the monitor and ensures that no stray light is distorting your color perception. However, some shops have noted a significant drop in productivity when they force their employees to work in dark, windowless rooms.

Consistency is more important than the absolute color temperature of the light source. If you work in a studio with a skylight and floor-to-ceiling windows, the color of the light will change over the course of the day, and your perception of color will change along with it. In a situation like that, you really need to create an area where you can view prints and transparencies under a light source that's shielded from the ambient light. A hood to shield the monitor from stray reflections is also very worthwhile—a cardboard box spray-painted matte black may not be elegant, but it's every bit as effective as more expensive solutions, and it doesn't distort the color the way most antiglare shields do.

Context. Your color perception is dramatically affected by surrounding colors. Again, you can go to extremes and paint all your walls neutral gray. It's easier and more important, however, to make your desktop pattern a neutral 50 percent gray. Pink-marble, green-plaid, or family-snapshot desktop patterns may seem fun and harmless, but they'll seriously interfere with your color judgment. We also recommend not wearing Hawaiian shirts when you're making critical color judgments. Designer black, you'll be happy to know, is just great.

Display Adjustments

The ability to calibrate a display depends on the controls that can affect its behavior. You can calibrate any display by changing the lookup tables in the video card that drives it, but the glaring weakness in this approach is that most video card lookup tables (LUTs) use 8 bits per channel. Just as with image editing, making adjustments always results in fewer levels than when you started, so when you only have 8 bits per channel, you need to preserve levels by putting the 8 bits per channel through as few adjustments as possible.

General LCD Monitors. Most professional LCD monitors have no physical adjustments other than the brightness of the backlight. With this type of display, it makes the most sense to profile its native, unadjusted behavior and let the color management system—which typically uses 20 bits per channel instead of the video card LUT's 8 bits—do the work of correcting the displayed colors. We provide some guidance on setting the backlight level in "Setting Aim Points," later in this chapter.

Some LCD monitors have additional color controls like those found on CRTs, which let you adjust options such as white point, contrast, and individual RGB levels. Don't use them! They're only there to pad out the feature list and provide the same convenience as CRT monitors, but in a color-critical workflow they'll probably degrade image quality, not enhance it. This is because those controls typically add an 8-bit adjustment step to your calibration and profiling routine, and as we've said, you don't want to add more conversions. Even if you did, you wouldn't want them happening at only 8 bits per channel. Just leave such a monitor at its native settings, adjust only the backlight, and let your calibration and profiling package do the rest.

High-End LCD Monitors. Some high-end LCD monitors—notably the EIZO FlexScan and ColorEdge series—contain their own lookup tables, independent of the video card, with 10, 12, or even 14 bits of precision. The extra bits don't let the monitor display more colors—the operating system pipeline through which applications communicate with the display is only 8 bits per channel wide—but they do let you calibrate the display to a specific white point and gamma without incurring the losses inherent in doing so in the 8-bit video card LUT. For these displays, we recommend a white point of D65, native gamma if it's an option, and gamma 2.2 if it isn't.

LED-Backlit Monitors. These monitors use arrays of LEDs for the backlight instead of a fluorescent tube. Some LED backlights use white LEDs, but better models use separate arrays of red, green, and blue LEDs, which are capable of much larger gamuts than fluorescent-backlit displays. If your LCD has a white-LED backlight, expect to calibrate it like a fluorescent-backlit LCD—you'll probably be able to calibrate only the display brightness, leaving everything else up to the profiling step. With the superior RGB-array LED backlights, you should be able to adjust the white point by varying the strength of the red, green, and blue LEDs. RGB-array LEDs are found in desktop monitors, while notebooks and other compact displays use white LEDs because they are smaller and lighter, though less adjustable.

CRT Monitors. High-end CRT displays are essentially no longer made, but there are still CRTs in good working order out in the field. For CRT displays which allow separate control over the RGB guns, we recommend adjusting the three RGB gains to achieve the desired white point and destination luminance. The gamma value, however, can be achieved only by adjusting the video card LUT during the profiling stage. If the profiling package offers native gamma as an option, use it. Otherwise we recommend choosing gamma 2.2 because it's closer to the native gamma of CRT displays than any of the other likely choices and hence involves smaller tweaks to the video card LUT than other gamma settings do.

Profiling Tools

If you're serious about working visually with Photoshop (rather than just going by the numbers), you'll get the best results if you use a profiling package that includes a hardware measurement device. Various eyeball-based profiling utilities (such as Apple Display Calibrator software) are available, but they have two major drawbacks:

Most are designed for CRT displays and don't do a good job of estimating the tonal response of LCDs.

TIP

Adobe Gamma was an eyeball-based calibrator included with earlier versions of Photoshop. If you still have it, don't use it on LCDs. Adobe Gamma was designed for CRT monitors, and the mechanism it uses for estimating gamma doesn't work well on LCD monitors.
They use your eyeballs as the measurement device. Our eyes are highly adaptable, which is great for a mammal living on planet Earth but distinctly suboptimal when the goal is to set the monitor to a known state. Human eyes involuntarily and uncontrollably adapt as ambient lighting conditions change, so they aren't accurate enough for consistent color.

Colorimeters and spectrophotometers have none of the eye's wonderful adaptability, so they always produce the same answer when fed the same stimulus. For monitor calibration and profiling, that's a big advantage! If you must use eyeball-based tools, these guidelines may help improve the results:

Minimize your eyes' adaptability by profiling under the same lighting conditions each time you make a profile. Ideally, the monitor should be the brightest thing in your field of view. (This is always true, but it's particularly critical during profiling—see the sidebar "Creating a Consistent Viewing Environment.")
Warm up the display for at least a half an hour before profiling.
Many eyeball-based profiling tools take an existing profile as their starting point. Often, if you take an existing display profile built with the eyeball-based tool as your starting point, the end result is very bad indeed. Start with a known good profile.

Many people are reluctant to spend money on display profiling hardware and software. Unless you've trained yourself to color-correct by reading the Info panel, trying to save money by doing calibration and profiling by eye is a classic example of being penny wise and pound foolish. As with most things, when it comes to monitor-profiling tools you tend to get what you pay for, but even the least expensive instrumented package will return more accurate and more consistent results than any of the visual tools.

Setting Aim Points

Use the capabilities of your monitor as a guide in setting aim points for calibration and profiling. The goal is to change the video card LUT as little as possible so that you get the full 256 shades per channel that the operating system allows you to send to the monitor.

Aim Points and the Working Space. Some beginners think they need to calibrate and profile their monitor to the same specs as their working space. That's a mistake; the white point and gamma of your display are entirely independent of the white point and gamma of your working space. The color management system translates working space white point and gamma seamlessly to those of your display. The goal in setting white point and gamma for the display is simply to make the display behave as well as it can.

Monitor Brightness (White Luminance). How bright should your monitor be? Here are some factors that will help you set the appropriate level:

The monitor should be bright enough to provide comfortable viewing. Reasonable starting points are around 80 to 95 cd/m² for CRT and around 120 cd/m² for LCDs.
For an LCD monitor, you probably won't be turning the monitor brightness up all the way. For one thing, changing the brightness level typically changes the black level as well. Today's LCD monitors are capable of such high brightness that some less expensive monitors can't be made dark enough for a good black level. And anyway, full brightness wears out the backlight more quickly.

TIP

if your prints are always dark compared to your monitor, your monitor brightness may be set too high relative to the real-world brightness of the paper you're using. Try regenerating the monitor profile at a lower monitor brightness level.
Don't aim for a brightness lower than 75 cd/m² or you'll affect the accurate reproduction of highlights. If a monitor can't achieve at least 75 cd/m² after profiling, it's a candidate for replacement.

White Point. On the few high-end displays with genuinely adjustable white points, we recommend adjusting the display to a D65/6500 K white point. For more information, see the sidebar "How White Are Your Whites?" If the white point isn't adjustable in the display itself, as is the case with most LCDs, we recommend profiling with the native white point—it's usually very close to D65 anyway.

Gamma. We prefer to use native gamma as the aim point. If native gamma isn't an option, we use gamma 2.2, which is close to the native response of most monitors. (Actually, the tonal response curve of an LCD monitor doesn't really match a gamma curve, but if gamma is the only option, gamma 2.2 is still the best alternative.)

Perhaps in recognition of the fact that LCDs don't really follow a gamma curve, some profiling packages now offer more exotic tone-response curves. With "standard" LCDs that don't have their own internal LUTs, we still prefer using native gamma if possible. But if that isn't an option, or if you're using a display with internal LUTs that the profiling software can address, we encourage you to investigate these options. We've obtained good results using the L* curve in Integrated Color Corporation ColorEyes, and with the DICOM curve in NEC's SpectraView II.

If You Just Want to Go by the Numbers. It's possible to do good work with Photoshop using an uncalibrated, unprofiled monitor. But to do this, you can't trust monitor colors at all. Instead go by the numbers, reading RGB levels and the CMYK dot percentages in the Info panel. Even with a calibrated monitor, it's a good idea to keep an eye on those numbers.

To set your monitor up for this old workflow, open the Color Settings dialog, select the RGB pop-up menu in the Working Spaces section, and choose Monitor RGB. We don't advocate this—we prefer the benefits of visual feedback—but it is possible, particularly if you're working in a closed-loop environment where you always go to the same output conditions. Of course, if you do this, you may as well ignore the rest of this chapter.

< Back Page 5 of 10 Next >

🔖 Save To Your Account

Peachpit Promotional Mailings & Special Offers

I would like to receive exclusive offers and hear about products from Peachpit and its family of brands. I can unsubscribe at any time.

Privacy Notice

Overview

Pearson Education, Inc., 221 River Street, Hoboken, New Jersey 07030, (Pearson) presents this site to provide information about Peachpit products and services that can be purchased through this site.

This privacy notice provides an overview of our commitment to privacy and describes how we collect, protect, use and share personal information collected through this site. Please note that other Pearson websites and online products and services have their own separate privacy policies.

Collection and Use of Information

To conduct business and deliver products and services, Pearson collects and uses personal information in several ways in connection with this site, including:

Questions and Inquiries

For inquiries and questions, we collect the inquiry or question, together with name, contact details (email address, phone number and mailing address) and any other additional information voluntarily submitted to us through a Contact Us form or an email. We use this information to address the inquiry and respond to the question.

Online Store

For orders and purchases placed through our online store on this site, we collect order details, name, institution name and address (if applicable), email address, phone number, shipping and billing addresses, credit/debit card information, shipping options and any instructions. We use this information to complete transactions, fulfill orders, communicate with individuals placing orders or visiting the online store, and for related purposes.

Surveys

Pearson may offer opportunities to provide feedback or participate in surveys, including surveys evaluating Pearson products, services or sites. Participation is voluntary. Pearson collects information requested in the survey questions and uses the information to evaluate, support, maintain and improve products, services or sites; develop new products and services; conduct educational research; and for other purposes specified in the survey.

Contests and Drawings

Occasionally, we may sponsor a contest or drawing. Participation is optional. Pearson collects name, contact information and other information specified on the entry form for the contest or drawing to conduct the contest or drawing. Pearson may collect additional personal information from the winners of a contest or drawing in order to award the prize and for tax reporting purposes, as required by law.

Newsletters

If you have elected to receive email newsletters or promotional mailings and special offers but want to unsubscribe, simply email ask@peachpit.com.

Service Announcements

On rare occasions it is necessary to send out a strictly service related announcement. For instance, if our service is temporarily suspended for maintenance we might send users an email. Generally, users may not opt-out of these communications, though they can deactivate their account information. However, these communications are not promotional in nature.

Customer Service

We communicate with users on a regular basis to provide requested services and in regard to issues relating to their account we reply via email or phone in accordance with the users' wishes when a user submits their information through our Contact Us form.

Other Collection and Use of Information

Application and System Logs

Pearson automatically collects log data to help ensure the delivery, availability and security of this site. Log data may include technical information about how a user or visitor connected to this site, such as browser type, type of computer/device, operating system, internet service provider and IP address. We use this information for support purposes and to monitor the health of the site, identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents and appropriately scale computing resources.

Web Analytics

Pearson may use third party web trend analytical services, including Google Analytics, to collect visitor information, such as IP addresses, browser types, referring pages, pages visited and time spent on a particular site. While these analytical services collect and report information on an anonymous basis, they may use cookies to gather web trend information. The information gathered may enable Pearson (but not the third party web trend services) to link information with application and system log data. Pearson uses this information for system administration and to identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents, appropriately scale computing resources and otherwise support and deliver this site and its services.

Cookies and Related Technologies

This site uses cookies and similar technologies to personalize content, measure traffic patterns, control security, track use and access of information on this site, and provide interest-based messages and advertising. Users can manage and block the use of cookies through their browser. Disabling or blocking certain cookies may limit the functionality of this site.

Do Not Track

This site currently does not respond to Do Not Track signals.

Security

Pearson uses appropriate physical, administrative and technical security measures to protect personal information from unauthorized access, use and disclosure.

Children

This site is not directed to children under the age of 13.

Marketing

Pearson may send or direct marketing communications to users, provided that

Pearson will not use personal information collected or processed as a K-12 school service provider for the purpose of directed or targeted advertising.
Such marketing is consistent with applicable law and Pearson's legal obligations.
Pearson will not knowingly direct or send marketing communications to an individual who has expressed a preference not to receive marketing.
Where required by applicable law, express or implied consent to marketing exists and has not been withdrawn.

Pearson may provide personal information to a third party service provider on a restricted basis to provide marketing solely on behalf of Pearson or an affiliate or customer for whom Pearson is a service provider. Marketing preferences may be changed at any time.

Correcting/Updating Personal Information

If a user's personally identifiable information changes (such as your postal address or email address), we provide a way to correct or update that user's personal data provided to us. This can be done on the Account page. If a user no longer desires our service and desires to delete his or her account, please contact us at customer-service@informit.com and we will process the deletion of a user's account.

Choice/Opt-out

Users can always make an informed choice as to whether they should proceed with certain services offered by Adobe Press. If you choose to remove yourself from our mailing list(s) simply visit the following page and uncheck any communication you no longer want to receive: www.peachpit.com/u.aspx.

Sale of Personal Information

Pearson does not rent or sell personal information in exchange for any payment of money.

While Pearson does not sell personal information, as defined in Nevada law, Nevada residents may email a request for no sale of their personal information to NevadaDesignatedRequest@pearson.com.

Supplemental Privacy Statement for California Residents

California residents should read our Supplemental privacy statement for California residents in conjunction with this Privacy Notice. The Supplemental privacy statement for California residents explains Pearson's commitment to comply with California law and applies to personal information of California residents collected in connection with this site and the Services.

Sharing and Disclosure

Pearson may disclose personal information, as follows:

As required by law.
With the consent of the individual (or their parent, if the individual is a minor)
In response to a subpoena, court order or legal process, to the extent permitted or required by law
To protect the security and safety of individuals, data, assets and systems, consistent with applicable law
In connection the sale, joint venture or other transfer of some or all of its company or assets, subject to the provisions of this Privacy Notice
To investigate or address actual or suspected fraud or other illegal activities
To exercise its legal rights, including enforcement of the Terms of Use for this site or another contract
To affiliated Pearson companies and other companies and organizations who perform work for Pearson and are obligated to protect the privacy of personal information consistent with this Privacy Notice
To a school, organization, company or government agency, where Pearson collects or processes the personal information in a school setting or on behalf of such organization, company or government agency.

Links

This web site contains links to other sites. Please be aware that we are not responsible for the privacy practices of such other sites. We encourage our users to be aware when they leave our site and to read the privacy statements of each and every web site that collects Personal Information. This privacy statement applies solely to information collected by this web site.

Requests and Contact

Please contact us about this Privacy Notice or if you have any requests or questions relating to the privacy of your personal information.

Changes to this Privacy Notice

We may revise this Privacy Notice through an updated posting. We will identify the effective date of the revision in the posting. Often, updates are made to provide greater clarity or to comply with changes in regulatory requirements. If the updates involve material changes to the collection, protection, use or disclosure of Personal Information, Pearson will provide notice of the change through a conspicuous notice on this site or other appropriate way. Continued use of the site after the effective date of a posted revision evidences acceptance. Please contact us if you have questions or concerns about the Privacy Notice or any objection to any revisions.

Last Update: November 17, 2020

Email Address