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I have a 2D image which contains R G and B values. I think this should be purely based on averaging of pixels and selecting the threshold to decided whether this is day picture or night one.

Can you provide any kind of different ideas to solve this problem?

Manish Kumar
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  • This is not a programming question - maybe try http://dsp.stackexchange.com ? – Paul R Jan 26 '15 at 19:15
  • It seems unlikely that your intended method can differentiate between a night-exposure and an under-exposed daytime one. How about using the EXIF information, if available? – Mark Setchell Jan 26 '15 at 19:20
  • @Paul: I had the same doubt while posting, should i delete this from here and post it to dsp.exchange? the question: http://stackoverflow.com/questions/2472467/how-to-find-one-image-inside-of-another encouraged me to ask the question – Manish Kumar Jan 26 '15 at 19:30
  • @MarkSetchell: Can you explain it in more detail? – Manish Kumar Jan 26 '15 at 19:32
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    A night-time image will be dark, so the mean RGB value will be low. An image that is underexposed (i.e the aperture was too small or the length of exposure too short) will also be dark, with a mean RGB value that is low. So, the average brightness is not a good discriminant between these two possibilities. – Mark Setchell Jan 26 '15 at 19:34
  • @ManishKumar: yes, good idea - DSP.SE would be the place for this question. – Paul R Jan 26 '15 at 20:17
  • This is simply too broad. Though Mark Setchell has provided a good heuristic on determining what is a day or night image, this criteria fails if, for example, it is night time in a room that is well illuminated (which he has already mentioned). There may be windows where you can clearly see that it's night time, but the illumination from light sources could interfere with the average RGB value. The same can be said with a day image with poor illumination. This ventures into the area of scene classification, which is more high level computer vision. Anyway, yes, DSP SE is a better fit. – rayryeng Jan 27 '15 at 03:46

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