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Wednesday, August 1, 2007

Luminosity Control In Photoshop

What does it take to visualize luminosity in black-and-white and color photography, then see and control it in Photoshop?

Optics In A  Digital World Luminosity is represented in a photograph by tones of black, white and gray. Luminosity is light. It represents all that we can see about the world we photograph. Every object, event and mood depends upon visible light represented by luminosity in the photograph.

Luminosity is important to visualize when we're taking a picture, transforming it in Photoshop, calibrating our monitor and printing. Because of the nature of visual perception, hue and saturation are processed separately from luminosity in our brains, and we must forcibly separate luminosity and train ourselves to see it to accomplish the quality we desire in a digital fine print. A good print starts with seeing the luminosity of a scene and ends with it.

Photographing Light
The photograph of the Matterhorn was made with a Kodak Instamatic camera in 1964 when I was 19 years old. This photograph has been one of my greatest teachers. I’ve kept it by my bedside for years and I’ve learned more about photography and the world from it than from all the hundreds of books or teachers or photographs I’ve known. It’s largely important because I made it before I knew anything at all about photography or ƒ-stops or film speeds or great photographers. It’s pristine vision. The camera was the cheapest Instamatic Kodak made (about $10, if I remember correctly). The film came in a cartridge that you dropped in, and the image size was one inch by one inch.

I knew at the instant I snapped the shutter that the photograph was a good one, at least visually. I’ve spent more than four decades trying to figure out why, and I’ve learned much. One of the most important things I’ve learned is about light and how to photograph it. That morning, looking at the Matterhorn, I discovered luminosity.

The light in this photograph has always been special to me, and I continually want to know why. The light seems to be a part of the scene and yet not part of it. How do we see this, and how do we, metaphorically, put ourselves in the path of its beam? The answer, for me, came from the aesthetic interpretation of two concepts that describe light: ambient light and reflected light.

Ambient light is the light from a light source (in this case, the sun) that falls upon the subject we’re photographing. Reflected light is the light reflected from the subject we’re photographing (in this case, the Matterhorn). The quality of both types of light is seen and represented differently in the black-and-white luminous tones of a photograph. Here’s what two great men have written about this peculiar phenomenon.

Luminosity Control In PhotoshopLuminosity Control In Photoshop

ABOVE: Luminosity as displayed through images 1 to 3. Figure 1 is the original scene as shown in color. Figure 2 reveals the same image as seen with the 90 viewing filter with most of the color subtracted. This monotone view helps to uncover the possibilities of the luminosity present within the image. Figure 3 is the final photograph as seen when converted into black-and-white.


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