Measuring the Light
To get your lighting just right, you’ll need to measure the precise level of illumination so that you can compare your lighting levels to those recommended in the ISO standards introduced in late 2000 (and outlined in Part 1) — 32 lux or 64 lux, as maximums.
You can purchase a special lux meter that numerically defines the illumination in a room, but many commonly used photographers’ exposure meters include printed lux/footcandle conversion tables affixed to the back, to allow their use for measuring light levels in lux.
Dr. Tim Padfield has devised a rather ingenious but complex process for calculating lux by using the reflective light meter built into most 35mm cameras. It’s far too dense to get into here, but you can check it for yourself at his Web site.
Whatever measuring device you use, the goal when installing lighting is to establish a precise and even level of illumination throughout the room. Measurements should be taken by holding the light meter just above various work surfaces or in front of a monitor. The precise level of light in viewing (proofing) booths or under task lamps used for proofing is governed by the ISO standards and obviously will need to be much higher than overall room lighting. However, task lamps or proofing booths should have lighting that is focused and does not spill onto the faces of monitors.
Calibrate Your Monitor
Once you’ve remodeled your editing room, it’s time to calibrate your monitor and establish a color-editing workflow. Most users will want to calibrate the monitor gamma and white point to one of two commonly used standards (2.2 gamma/6,500°K white point or 1.8 gamma /5,000°K). While personal preference is a factor, the final choice also will be affected by the degree to which you implement other viewing standards in your unique environment.
The 2.2 gama/6,500°K standard is perfectly acceptable and widely used, although whites on screen may appear to have a blue cast to some eyes. The more rigid 1.8 gama/5,000°K standard can reduce overall monitor brightness and the whites on screen may appear too yellow to some eyes, but it is preferred if you need to do professional pre-press proofing. The phenomena of whites appearing too blue or yellow on-screen is greatly reduced or eliminated when the editing environment is truly color neutral (neutral walls, D50 lighting, blocked window light, etc.). Ultimately, either monitor calibration standard will work, especially if you use Adobe Photoshop version 5.0 or later as your image editor (because it allows for a color space for image files separate from a monitor’s color space).
To calibrate, use either the free Adobe Gamma tool built into Photoshop or the Monitor Calibration tool built into Apple’s Monitors Control panel (but not both). Be aware that some applications (such as Adobe PageMaker) automatically install and turn on Adobe Gamma, and you may have to check to make sure that dueling calibration tools aren’t active.
Better yet, a hardware calibration device is more precise. Some monitors are sold with hardware-calibration pucks, either as standard equipment or add-ons. Third-party hardware calibration devices, such as the $224 Monitor Spyder by ColorVision, work well with a wide range of monitors. Of course, some hardware calibration systems are more sensitive (and accurate) than others. Budget and the degree of color accuracy required will affect your purchasing decision.
Remember, the whole idea behind ICC color — and a properly configured editing room — is to be able to use your monitor as a reliable soft proofing tool before you create a printed proof or final printed output.
Review the Actual Standards for Yourself
As noted in Part 1 of this report, the international standards that define environmental and lighting conditions in color editing facilities are in the process of being updated. While journalistic reports like this help end-users digest and analyze the standards, there may be no substitute for reading the actual specifications and precise language used by standards committees. If you’re concerned only about viewing images onscreen, you can safely limit yourself to ISO 3664:2000; if you need to compare images onscreen to printed output, the more appropriate standard for you will be ISO 12646.
ISO documents usually can be purchased through the ISO or any country’s national standards organization by credit card. In the U.S., technological standards ultimately are defined by ANSI (American National Standards Institute). Licenses to receive electronic copies (pdf files) of ANSI or ISO standards (including 3664:2000) can be purchased by phone (212-642-4980) or via the ANSI Electronic Standards Store, for a cost of $58. ANSI has appointed Global Engineering Documents of Englewood, Colo., its primary distribution source for selling printed copies of standards and technical documents, which are available by FAX or mail. Global can be contacted at (303-397-7956) or through e-mail (gl****@*hs.com).
Read more by George Wedding.
This article was last modified on January 18, 2023
This article was first published on March 6, 2001
Commenting is easier and faster when you're logged in!
