Microscopy Primer
Light and Color
Microscope Basics
Special Techniques
Digital Imaging
Confocal Microscopy
Live-Cell Imaging
Photomicrography
Microscopy Museum
Virtual Microscopy
Fluorescence
Web Resources
License Info
Image Use
Custom Photos
Partners
Site Info
Contact Us
Publications
Home

The Galleries:

Photo Gallery
Silicon Zoo
Pharmaceuticals
Chip Shots
Phytochemicals
DNA Gallery
Microscapes
Vitamins
Amino Acids
Birthstones
Religion Collection
Pesticides
BeerShots
Cocktail Collection
Screen Savers
Win Wallpaper
Mac Wallpaper
Movie Gallery

Concepts in Digital Imaging Technology

Sequential Three-Pass Color CCD Imaging

Three-pass sequential color CCD imaging systems employ a rotating color wheel to capture three successive exposures in order to obtain the desired RGB (red, green, and blue) color characteristics of a digital image. The major advantage of this technique is the ability to fully utilize the entire pixel array of a CCD imaging chip, by using one pass for each color.

Silicon based charge-coupled devices lack the ability to distinguish color information presented to the pixel elements by incoming photons. Even though electromagnetic radiation of varying energy passes through the devices to a depth determined by the wavelength, the interaction that produces free elections and holes is not color sensitive. A typical sequential color imaging system design is illustrated in Figure 1, which shows the red filter being used to pass illuminating light waves from the microscope optics to the CCD surface. The primary advantage of this technique is the ability to achieve the highest resolution capable of the device, which equals the size of the CCD array.

After all of the image information has been captured in three individual passes, it is recombined off-chip and processed in a manner similar to that of other CCD architectures. The major disadvantage of this system is the relatively long exposure times necessary to accumulate three individual color arrays, which requires an almost stationary subject and vibration-free operation of the rotating color wheel mechanical components. This technique is being slowly phased out as single-shot CCD cameras with higher resolutions become commonplace. However, a number of applications now incorporate a rapidly switchable liquid crystal array screen that can be used to capture the three colors in milliseconds, thus speeding the throughput of the device and reducing the risk of mechanically-induced vibration.

Contributing Authors

Mortimer Abramowitz - Olympus America, Inc., Two Corporate Center Drive., Melville, New York, 11747.

Michael W. Davidson - National High Magnetic Field Laboratory, 1800 East Paul Dirac Dr., The Florida State University, Tallahassee, Florida, 32310.


BACK TO CONCEPTS IN DIGITAL IMAGING TECHNOLOGY

Questions or comments? Send us an email.
© 1998-2013 by Michael W. Davidson and The Florida State University. All Rights Reserved. No images, graphics, scripts, or applets may be reproduced or used in any manner without permission from the copyright holders. Use of this website means you agree to all of the Legal Terms and Conditions set forth by the owners.
This website is maintained by our
Graphics & Web Programming Team
in collaboration with Optical Microscopy at the
National High Magnetic Field Laboratory.
Last modification: Friday, Jul 16, 2004 at 08:16 AM
Access Count Since June 30, 2000: 25196
Visit the websites of our partners in digital imaging education:
Visit the Olympus Microscopy Resource Center website. Visit the QImaging website.