Power Generator
Imaging Lens
Image Sensor
Polyoptic Wheel
Viewfinder, Eye
LED Flash
LCD Display
Image Processing

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Introduction      Pixel      Image Readout      Color
Sensing Color      Illustrations

Understanding Color

Figure 5: Color mixer

Our eyes can perceive a few million colors. Remarkably, most of these colors can be produced by mixing just the three primary colors of light − red, green and blue − in varying proportions [1]. The demo in Figure 5 shows this phenomenon. Use the sliders to control the amount of each primary color. Think of a color. Can you guess how much of red, green and blue would be needed to make that color?

This demonstration gives us a hint of how we might use our (color blind) image sensor to measure color. If we place a red filter (red-tinted clear plastic) in front of the image sensor, we would get an image where each pixel measures the amount of red light falling on it. If we now take two more images using a green and a blue filter, each pixel would have measured the amounts of red, green and blue light falling on it. These three images together represent a color image of the scene. But, is there a way to capture the same information by taking just one image instead of three?



[1] H. Helmholtz, Physiological Optics – The Sensations of Vision, 1866, as translated in D. L. MacAdam, Sources of Color Science, Cambridge MIT Press, 1970.