Thursday, July 18, 2013

Dealing with camera noise

If you read “Why camera noise matters” you’ll know noise can be a problem. You may also be wondering what to do about it.
Allow me to offer three suggestions:
  1. Buy a camera with lower noise.
Easier said than done. Camera-makers don’t always make their noise levels available, especially if they’re nothing to write home about. And don’t go thinking it’s all just sensor-dependent: some of the noise comes from the camera electronics rather than the chip itself. That’s why, as a general rule, more expensive cameras produce better images.
  1. Average multiple images.
I like this approach. Assuming time permits, grab two images and average them. It takes a little computational effort, especially when you’re in the multi-megapixel range, so I don’t think a smart camera is up to the task, but if you have a PC system it might be a quick way to reduce variation.
  1. Lower the temperature.
Much of the noise is temperature related. In fact a good rule of thumb is that noise doubles with every 6 to 8 oC rise. So keep the camera cooler and the images will be less noisy.
Stuck for ideas how to lower the camera temp? Well here are two. Mount it on a big chunk of aluminum, or put it in an air-cooled enclosure.
Noise can really mess with your images and inspections, but there are ways of dealing with it. I’ve offered a couple of suggestions. If you others, please share.


Anonymous said...

Long exposures (integration times) increase noise as well. Keep the are well lighted to keep exposure times short.

Anonymous said...

Long exposures (integration time) can lead to increased noise. Keep the area well lit for shorter exposure times.