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mvcisback / SSLVC

Sound Source Localization using Visual Cues
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Removing Brightness Fluctuations #4

Closed mvcisback closed 10 years ago

mvcisback commented 10 years ago

Brightness fluctuations in the scene cause superfluous changes between frames.

Please discuss and post results of relevant experiments here.

To combat this we've discussed a few options:

ghost commented 10 years ago

http://en.m.wikipedia.org/wiki/Histogram_equalization It's to adjust contrast, it might not be as useful for a series of frames, but worth a shot.

On Friday, October 24, 2014, Marcell Vazquez-Chanlatte < notifications@github.com> wrote:

Brightness fluctuations in the scene cause superfluous changes between frames.

Please discuss and post results of relevant experiments here.

To combat this we've discussed a few options:

  • Histogram Equalizing Need more information as to what this is
  • Simple threshold that gradient must pass before being considered a change
  • Changing color spaces and then projecting away the brightness information
    • HSV
    • YUV
    • Sunglasses (also to demonstrate that gifs and images can be embedded)

https://camo.githubusercontent.com/3dd1600aefe453dbd2d4335be41f4d2c13f9fc09/687474703a2f2f6d656469612e67697068792e636f6d2f6d656469612f554d7175326c304c6e5a66596b2f67697068792e676966

— Reply to this email directly or view it on GitHub https://github.com/mvcisback/CS598ps_project/issues/4.

Thanks, Best Regards, Ramin

ghost commented 10 years ago

A good paper on image preprocessing. http://cmp.felk.cvut.cz/~flachbor/teaching/cv_int_rob/bright_geom_transf.pdf

mvcisback commented 10 years ago

@ramili I think it may be worth a shot.

  1. I wonder how stable they are. Because we're comparing across scenes (where the lighting may in fact change), the base line of comparisons is important.
  2. They only seem to demo on grey scaled images. I wonder how well these work in more complicated color spaces.
ghost commented 10 years ago

exactly! comparing across scenes is going to be a problem. There might be ways to apply hist eq across all frame with respect to a ref frame. If you assume the lighting doesn't change drastically during the speech, then applying them individually should be okay too. Something to play with. On matlab you can use "histeq" to do that. http://www.mathworks.com/help/images/ref/histeq.html

mvcisback commented 10 years ago

We're going to use a face recognition system as a black box that presumably handles this. Thus closing