Points, Pixels, and Gray Levels: Digitizing Image Data

  • James B. Pawley


Microscopical images are now almost always recorded digitally. To accomplish this, the flux of photons that forms the final image must be divided into small geometrical subunits called pixels. The light intensity in each pixel will be stored as a single number. Changing the objective magnification, the zoom magnification on your confocal control panel, or choosing another coupling tube magnification for your charge-coupled device (CCD) camera changes the size of the area on the object that is represented by one pixel. If you can arrange matters so that the smallest feature recorded in your image data is at least 4 to 5 pixels wide in each direction, then all is well.


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. Janesick, J., 2001, Scientific Charge Coupled Devices, SPIE Press, Bellingham, WA. Vol. PM83 1–920 pages.Google Scholar
  2. Lamontagne, N.D., 2004, Is it right for you? Biophotonics International, 11(1):38–42.Google Scholar
  3. Nyquist, H., 1928, Certain topics in telegraph transmission theory. Trans. AIEE 47:617–644.Google Scholar
  4. Robbins, M.S., and Hadwen, B.J., 2003, The Noise Performance of Electron Multiplying Charge Coupled Devices, IEEE Trans. Elect. Dev. 50(5): 1227–1232.CrossRefGoogle Scholar
  5. Shannon, C.E., 1949, Communication in the presence of noise, Proc. Inst. Radio Eng. 37:10–21.Google Scholar

Copyright information

© Springer Science+Business Media, LLC 2006

Authors and Affiliations

  • James B. Pawley
    • 1
  1. 1.University of WisconsinMadisonUSA

Personalised recommendations