The Visible Spectrum: What Your Camera Sees

I’ve had a number of requests to explain (in layman’s terms) some of the principles of color science as they apply to photography. The more you understand about the science of light and color behind the art of photography, the more you will know how to use that light to your best advantage when shooting with your camera. This post will be the first in a series of short lessons that will help you understand what’s happening behind the lens. This brief session will be introduced by a short clip from the GottaKnow Light series of videos.

As you just heard, your eyes can only “see” the colors of the visible spectrum; the same colors that are visible in rainbows. Rainbows are actually refracted white light. When we place a prism in front of a white beam of light, the components of white light are split into individual colors.

Volleyball-RGB

The truth is, your camera doesn’t actually capture color images at all. It captures three images of monochromatic light as seen through individual Red, Green, and Blue filters. These three colors are projected onto millions of microscopic sensors behind the lens of your camera. These sensors (called photosites) are located on a microchip called an image sensor. Each sensor records either a red, green, or blue portion of the scene’s light. The strength of light recorded on each R, G, or B sensor is measured in lumens; the smallest metric of light measurement.

Image Travel-CameraEach photosite on this sensor then sends its information to the camera’s image processor which interprets the signals as a grid of colored pixels known as a bitmap. The color of each pixel in this bitmap is defined as one of millions (or even trillions) of colors, depending on whether the image was recorded as an 8-bit JPEG image or 14-bit RAW data file (the difference between 256 and 14,000). The file is then saved onto the camera’s memory card. If the file was saved in RAW format, a generic interpretation of this color information is displayed as a JPEG image when the image is opened in a RAW interpreter like Adobe Camera Raw or Lightroom. A more full explanation of JPEG vs RAW captures will be presented in a later post.

Now you’ll probably understand better what the RGB initials stand for. This all started with the camera lens spreading the light of the scene over the surface of the image sensor. And now it will be clear why your camera’s sharp focus is so important. If the subject isn’t in clear focus, the pixels in your image will record fuzzy. And you can’t sharpen fuzzy! I’ll cover more of the science in following posts. This should give you an appreciation for the magic of digital camera technology.

Just thought you’d like to know. Let me know if this makes sense to you.

If you’d like to understand even more of what makes color work, how light behaves, and how easy it is to shape the light in your photographic images, here’s a suggestion. I’ve created a very entertaining and easy-to-understand video series that will teach you the fundamentals of light and color and help you to capture and produce amazing color. Go to http://gottaknowvideos.com and get Bright About Light!

About Herb Paynter

Herb is a published author, photographer, retoucher, color reproduction specialist and a regular writer for Digital Photography School. Download his iBook Digital Color Photography from the iTunes store and view his Light and Color video series at Gotta Know Videos.com.
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