COLOR CORRECTION

COLOR CORRECTION AND CALIBRATION

Color correction and color calibration are two activities that are often confused with (or passed off as) color management. They are very important to the activity of getting "pretty pictures" and as such need to be part of any useful color management scheme.

Color Correction

What the name implies is that you're "correcting" something that was wrong. Well, if it ain't broke, you don't want to fix it, so we need to consider what sort of color problems might need "correcting".

Consider the image below. This sort of white point correction problem is certainly very common, in fact it is by far the most common correction needed in digital imaging. Other kinds of correction, such as adjustments to "saturation" or "hue", are common as well, and are also available in software products such as Adobe Photoshop® and Wasatch SoftRIP.

White Point

Illustration 1

Color Calibration

Daily variations in printing conditions can leave you with a lot of dot gain, as shown in Illustration 2, or dot loss, as shown in Illustration 3.

Dot Gain

Illustration 2: Dot Gain

Dot Loss

Illustration 3: Dot Loss

If you are confronted with such variations on a daily basis, you need a quick way to adjust. The test pattern shown in Illustration 4, which is distributed with Wasatch SoftRIP, is the typical foundation for such color calibration activities.

Test Pattern

Illustration 4: Test Pattern

This pattern is quickly scanned with a strip reading densitometer, or with another direct–interface densitometer, such as the X–Rite EyeOne, or may even be entered to the computer by hand. Software algorithms are executed to produce tone–curves which return the printing process to a standard linear behavior.

This sort of "daily target" adjustment is common to advanced color management systems such as Wasatch SoftRIP print management software, and X-Rite and Barbieri color profile authoring software. In Wasatch SoftRIP, it is provided completely independently of both correction and color management, as described below.

Putting It All Together

Color correction, color management, and color calibration all need to be combined to create a powerful color reproduction system.

When you install a Wasatch Imaging Configuration, you are getting four of the six components shown in Illustration 5. For the RGB components of your incoming graphics, you are getting a link that simulates a calibrated RGB source, or idealized computer monitor. For the CMYK components, you are getting an advanced link that simulates the behavior of a SWOP proofer, allowing you to hit the named–and–numbered spot colors found in color swatch books. All this is built upon the foundation of the final linearization (calibration).

RGB & CMYK

The elements at the beginning of the pipeline, the color corrections, are left for you to edit on a job–by–job basis, as needed to correct for the jobs that you receive.



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