How Digital Cameras Work

By: Karim Nice, Tracy V. Wilson & Gerald Gurevich

CCD Camera Summary

A memory stick
Photo courtesy HSW Shopper

It takes several steps for a digital camera to take a picture. Here's a review of what happens in a CCD camera, from beginning to end:

  • You aim the camera at the subject and adjust the optical zoom to get closer or farther away.
  • You press lightly on the shutter release.
  • The camera automatically focuses on the subject and takes a reading of the available light.
  • The camera sets the aperture and shutter speed for optimal exposure.
  • You press the shutter release all the way.
  • The camera resets the CCD and exposes it to the light, building up an electrical charge, until the shutter closes.
  • The ADC measures the charge and creates a digital signal that represents the values of the charge at each pixel.
  • A processor interpolates the data from the different pixels to create natural color. On many cameras, it is possible to see the output on the LCD at this stage.
  • A processor may perform a preset level of compression on the data.
  • The information is stored in some form of memory device (probably a Flash memory card).


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More Great Links


  • HP Digital Photography Center
  • Tech Digest
  • Photo.Net: Digital Cameras - A Beginner's Guide
  • Photo.Net: Size Matters
  • Introduction to Digital Photography
  • PC Magazine: Inside Track,1759,1822946,00.asp
  • Camera Resolution Chart