Pictographics Color Edit

Pictographics Color Edit is the color engine behind PictoColor Corporation's award winning iCorrect® EditLab Pro Plug-in, iCorrect® EditLab ProApp Stand Alone Application products.  The best way to gain an understanding of the Pictographics Color Edit Library is to download the demo version of iCorrect EditLab ProApp 6.0 or by purchasing a copy of one of the iCorrect EditLab Pro products at PictoColor's web site, http://www.pictocolor.com.

iCorrect EditLab is a color correction and color editing program. iCorrect EditLab makes global color corrections based on:

• an automatic analysis of your image,
• analysis of certain reference or "memory" colors that you identify in your image,
• interactive dialog control settings, and
• EditLab's or Photoshop's color management setup.

EditLab works in "SmartColor" mode (a mode that intelligently sets the editing controls based on the color content of the image), in manual mode, or in a combination of the two.

Many of the tools and much of the philosophy behind EditLab are the result of the observation that almost everyone knows what certain colors should look like. When an image is viewed, it is surprising how easily color errors are seen, even by people untrained in this discipline. For example, everyone knows that snow is white (neutral) and what skin, foliage, and sky blue should look like. If an image shows a person's face that is bright red, the observer knows that the color is wrong, even though he may never have seen the actual person in the image. These common reference or "memory" colors form the basis of EditLab's approach to improving the color of an image. EditLab's tools include:

• color balance;
• black and white point selection;
• brightness/contrast/saturation controls; and
• hue selective editing.

In many production environments color management, using ICC device profiles, is rapidly becoming the preferred method of producing color-accurate digital images. While this may be the best way to control color reproduction in many situations, it isn't always possible. There are large classes of digital images of unknown pedigree. It is not possible to use device profiles to relate the colors in these images to any device-independent reference because the profiles do not exist and cannot be made after the fact. For example, you may not have any information about how images on a stock photography CD-ROM were acquired. EditLab can be used to quickly and easily correct uncalibrated images such as these, transforming them into a calibrated color space.

Color Correction Stages

The functional organization of the Pictographics Color Edit library is that color correction occurs as a fixed-order pipeline of stages, where each stage is controlled by parameters, which may be set according to the content of the image being corrected.  For each of these stages, there exist parameter values that cause the stage to have a null behavior, that is, values that cause the input color entering the stage to pass through to its output without change.

The stages are connected in this order:

1. Linear Mode Correction
2. Color Balance
3.  Black Point
4. White Point
5. Brightness
6. Contrast
7. Saturation
8. Hue Selective Edits

In iCorrect EditLab implementations, these stages are grouped into four tool panels.  But this is a GUI decision only.  Al stages are active and functioning in the order shown above.

Automatic Settings

There exist library functions that attempt to make good first guesses for many of the parameters controlling the color correction stages.  In the iCorrect EditLab implementations, this facility is called SmartColor™. Since these functions are adaptive to the content of the image, a representative bitmap of the image (usually scaled down from a higher resolution original) must be supplied to the function for analysis.

Colorimetric RGB

Foundational to the whole library’s approach to color correction is the notion of a colorimetric RGB.  Much like the RGB working space found in Adobe Photoshop, the library requires the RGB system to have an unambiguous colorimetric meaning by tying it to the CIE color system.  This allows the color correction to have meaning to other programs afterward, and it also allows for the possibility of properly displaying the color image for the user by taking into account the monitor profile.

Memory Colors

The Hue Selective editing stage allows the hue, brightness and saturation to be adjusted in a way that affects only a limited range of hues, leaving other hues and neutrals unaffected.  For a given starting hue, its new hue, brightness and saturation may be changed to achieve a new color.

Although this may be done by manually adjusting parameters to achieve a goal, the library also has facilities built into it that permit the software to find the best settings to achieve a predetermined goal, thus removing the need for trial-an-error adjustments.  These predetermined target colors are called memory colors and are used for any useful colors, such as skin tones, foliage, sky or the colors of the jerseys worn by a sports team.

When this facility is used, a source color is identified and associated with a colorimetrically described memory color definition and the software will make the hue selective adjustments needed to most closely match the two.

Licensing Information

For information on licensing Pictographics Digital Color Technology please contact us.