When is orange more like red? Web designers, even picky ones, sometimes ignore color shift across monitors.

How is a web designer to manage color when the screens of their users could be any size or color or could be viewed under any lighting conditions?

Unlike fixing HTML errors, which affect browsers as the page is loaded, getting accurate color is part of the designer’s work process.

Maintaining colors across projects is possible once the problems are understood. Read on for the challenges—and solutions—to getting consistent color on the web.

Can you spot the difference between the photos below?

One of the images is slightly more blue than the other. This “color shift,” or overall tint of a particular hue, might go unnoticed by the casual observer. After all, a slight change in hue doesn’t make this any less of a flower or detract from the dewdrop’s detail. It’s a cumulative change.

Over time, maximum-quality JPEG images and 256-color PNG icons eat up precious bandwidth. Complexity in HTML increases the browser’s workload with each page load. Unlike these problems, which add up as visitors browse the website, color management is a problem with the design process. Images created on an uncalibrated monitor become inconsistent over time.

Color shift could go by another name: inattentiveness.

When can we say that a graphic’s color matches the page close enough? At what point is a photo’s color too inaccurate? What details don’t matter to the project as a whole? Everyone may have different answers, but no one who takes digital images seriously can ignore color calibration.

The print industry has struggled with getting accurate color for decades. Ensuring that the exact same colors appear at all stages of production—including in various monitors, office printers and high-end presses—has spawned its own industry of calibration devices, software solutions and even ISO standards.

The web design community generally doesn’t worry about press checks. But maybe it should.

The Web Has Had Color Issues Since It’s Had Color

In the 1990s, getting accurate color on the web meant using a palette of 216 “web-safe” colors. These hues and shades were (mostly) guaranteed not to dither when displayed on monitors that could not handle more than 8-bit color.

Above is a gradient with and without dithering. Today, the vast majority of computers can show 24-bit color or better (according to these browser display statistics and Google Analytics tracking of websites, including Webdesigner Depot). That is, each pixel can show one of millions of colors, making calibration both complicated and more critical.

The web has long relied on hexidecimal codes, like #F35C23, to define colors. These six-character strings can display a wide variety of hues and values with great precision. An image that has #F35C23 and a CSS background in #F35C23 will match perfectly.

The problem is that the code defines a combination of red, green and blue but does not always result in consistent color. Display screens account for the difference.

White Is White, Except When It Isn’t

Many factors affect color accuracy when creating and editing digital images. As with print, color on the web depends on the environment in which the image is created. Unlike print, web-based images can change every time they’re displayed because the monitors of users will vary, and no press check can catch problems that crop up.

Although many modern web browsers can display CMYK images, most images for the web are based on the additive RGB color model. This model applies a mixture of red, green and blue to each pixel.

But not all monitors are built the same, and so a particular shade of orange could be inconsistent across different screens. Here are some of the causes of color change:

• Slight changes between manufacturers and models account for slight inaccuracies in shade and hue.
• Many screens (especially CRT monitors) change color over the years and even as they warm up over the course of a day.
• Until recently, Mac OS X and Windows used two different “gammas,” which meant that images on Macs appeared brighter than ones on PC. Mac OS X 10.6 (Snow Leopard) uses the more common gamma of 2.2, which is the same as Windows and many televisions and camcorders.
• People browse the web from many different locations and in many different lighting conditions. The effect of overhead lights and the amount and color of natural light all affect the appearance of color on the screen.

Above, different calibration shows that “white” is often an assumed color:

1. The original image, shot under fluorescent light with a point-and-shoot camera.
2. Approximate color shift on a Mac before Snow Leopard.
3. Approximate color shift on an aging CRT monitor.
4. Close to true color, as seen on the laptop on which the photo was processed. Seguir leyendo “How to Calibrate Color for the Web” →