Signal Processing Stack Exchange is a question and answer site for practitioners of the art and science of signal, image and video processing. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

I need to make an application in iphone which needs to calculate noise, geometric deformation other distortions in an image. How to do this? I have done some image processing stuff with opencv + iphone. But I dont know how to calculate these parameters.

1) How to calculate noise in an image?

2) What is geometric deformation and how to calculate geometric deformation of an image?

3) Is geometric deformation and distortion are same parameters in terms of image filter? or any other distortions available to calculate an image is good quality or not?

share|improve this question
Please don't cross-post your question to multiple SE sites. – nikie Feb 11 '13 at 11:22
@nikie Link to cross-posted question? – Phonon Feb 11 '13 at 23:00
Good point.… – nikie Feb 12 '13 at 7:19
  1. You should do it on a known set of calibration targets. For example, this type of calibration target is being used to measure noise. You should find the patches locations, and measure the noise by some metric. If you don't know any metric, you can start by browsing DXOlabs site, or Imatest site. enter image description here

  2. I guess that you mean radial distortion. Radial distortion can be found by a process called camera calibration, by using a known target such as checkerboard. For more info, see Camera Calibration Toolbox. Here is an image from another software that does it: enter image description here

  3. I didn't understand your question at all. Please reprase it and add more information.

share|improve this answer
+1 for giving such a detailed answer despite 3.Can you offer some suggestions that don't depend on matlab for image calibration? – Magpie Feb 15 '13 at 3:40
@Magpie, try OpenCv. It contains camera calibration functions. – Andrey Rubshtein Feb 16 '13 at 9:29

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.