ClarkVision.com

Home Galleries Articles Reviews Best Gear Science New About Contact

Effects of Dust and Hot or Stuck Pixels on Digital Camera Images

by Roger N. Clark

All images, text and data on this site are copyrighted.
They may not be used except by written permission from Roger N. Clark.
All rights reserved.


This page shows examples of dust on "the sensor" of a digital camera as well as hot or stuck pixels. The dust is actually not on the sensor, but on the blur filter that covers the sensor. Stuck pixels are the same value regardless or exposure length or light intensity. Hot pixels are pixels with a higher dark current and increase in intensity with longer exposure time and hotter temperatures, again regardless of incident light. Hot pixels become more noticeable with high ISO low light images of long exposure and higher temperatures.

Examples



image dust.over.sensor.4x.jpg
Figure 1. Examples of dust on a digital camera image. The size of the spot is somewhat constant for small dust specs and depends on the f/ratio of the lens. This image is at f/16. At f/4 no dust is seen. The dust spots are generally dark gray. This image is a 4x enlargement using nearest neighbor sampling. Canon 1D Mark II camera. Note the size of the spots in this image compared to those in Figure 2. Two portions of a larger image are shown here, and the division line where they were combined shows shows as a change in the background level.



image hot.or.stuck.pixels.samples.4x.jpg
Figure 2. Example hot or stuck pixels. A red or blue pixel comes out as an interpolated small spot of uniform color. A green pixel comes out white with a single bright pixel with 4 fainter ones in a regular pattern. This is for a Canon 1D Mark II camera, although I have seen this pattern with other cameras. This image is a 4x enlargement using nearest neighbor sampling. Note the size of the spots in this image compared to those in Figure 1.


Home Galleries Articles Reviews Best Gear Science New About Contact

http://www.clarkvision.com/articles/dust.on.sensor

First Published April 20, 2009
Last updated April 20, 2009.