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Monday, March 3, 2008

Color Choice: Luminance, Chrominance And Hue

Among the tools at your disposal, the LCH Editor gives you a powerful weapon for finessing the color relationships in your images

This Article Features Photo Zoom

In a previous article, I explained “Color Choice Isn't By Chance” (Digital Photo Pro, July/August 2007). The premise is that today's digital photography hardware and software provide a plethora of features and performance that interact to enable more control and creative options than ever before. When you understand how each tool operates, and how combinations of tools can interact, you have the opportunity to enhance original images as never before. First, I'll discuss the individual tools in the LCH Editor and later explain and experiment to show how they interact to provide extended creativity. We'll limit our initial expectations, and then with greater depth of understanding, expand our ideas.

LCH stands for Luminance, Chrominance and Hue, which are three of each image's basic characteristics, affecting the viewer's perception of color. Although color enhancements (fabrications) can be worked on with the LCH Editor, here I'll discuss the original color that exists in an image file, not fabricated color. We'll see how the LCH Editor's tools can be used to enhance existing color, adding to an image's visual vibrancy. The following will provide you with a basic understanding of what each tool can do so you can begin to choose and dissect your images, learning how and when to apply each tool. Then I'll experiment with pictures to provide a visual experience about how the tool can change images.

The LCH Editor's Tools
Luminance refers to an image's brightness. From a technical perspective, one tries to render an image to a brightness that corresponds to the original subject and its lighting. However, from the point of view of creativity and with digital photography tools, it's possible to alter the image and make the entire image brighter or darker than the original source. It's also possible to alter selected portions of the image, as in the historical technique of dodging and burning a print. As a result, by manipulation of luminance, you can alter the image dramatically or subtly, as you wish. In consideration of the image's aesthetic qualities, I recommend that you carefully consider to what extent you'll change the image's luminance and avoid making it look “odd,” that is, unless you want it to look “odd.”


Figure 1: Fish under Coral is a classic wide-angle composition that screams for adjustments to balance the scene's range of brightness and bring out color vibrancy and details in the darker areas.


Figure 2: I used the Color Lightness tool to darken the red spectrum area of the fish by concurrently using a painting tool to selectively apply the change.



Figure 3: I used the Color Lightness tool in the blue spectrum area to change the appearance of the sky above and the water below.


This wide-angle view, taken with the Nikonos 15mm lens, is a classic perspective, with the wide-angle revealing details above and below the coral reef. The side-by-side image illustration shows a before and after comparison.