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  1. #1
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    compare 2 images

    Hello,
    I want to compare two jpeg images (C + +).
    pixel by pixel? how??

  2. #2
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    Re: compare 2 images

    See this thread opened some days ago:
    http://discussion.forum.nokia.com/fo...d.php?t=162539

  3. #3
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    Re: compare 2 images

    Thank you for the answer
    What I understood from this link that the comparison pixel by pixel is not the right solution? no alternative
    please i need your help.

  4. #4
    Nokia Developer Moderator
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    Re: compare 2 images

    Have you considered a Google search for "image comparison algorithm". The problem is not at all mobile or Symbian specific, you just have to find the best technical solution and then make it work on the mobile environment.
    -- Lucian

    If you are not yet a DVLUP member it is time to correct that mistake :) Click here to join: http://www.dvlup.com/lucian/Invite

  5. #5
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    Re: compare 2 images

    ARGH.

    WHAT do you want to achieve by the comparison? Do you just want to see if they are coming from the same file, or do you want to perform more advanced comparisons?
    The lines above are the best I have to offer.If anyone of you is of more advanced knowledge, I ask for your patience and understanding! - unknown arab poet
    http://www.tamoggemon.com - Symbian blog - Windows Phone blog
    My other blogs:
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  6. #6
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    Re: compare 2 images

    Thank you ,
    I want to compare the contents of two images to detect movement
    example :I have a reference image and I want to compare each time with another captured by the cam

    sorry for my bad English

  7. #7
    Nokia Developer Moderator
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    Re: compare 2 images

    Have you done your research, as already recommended above? Here's another link for you: http://en.wikipedia.org/wiki/Motion_detection See the reference links at the bottom of the article.

    Also, see http://discussion.forum.nokia.com/fo...d.php?t=114449
    Last edited by ltomuta; 2009-03-31 at 01:03.
    -- Lucian

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  8. #8
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    Re: compare 2 images

    Planar offset of one image relatively to another generally computed by Fourier phase correlation
    http://en.wikipedia.org/wiki/Phase_correlation
    You have to write or port FFT library to your application (Nokia CV library have no FFT) or if you have access to DSP you can use it instead)
    http://en.wikipedia.org/wiki/Fast_fourier_transform
    You can also write simple Fourier Transform implementation if performance not an issue.
    And after that use it to calculate phase correlation (some libraries already have it built in).
    There is a huge number of open sourced FFT libraries on the net.

    There is another, more complex and less robust method - extract feature points from image, fit corresponding points on both images and calculate movement.
    http://en.wikipedia.org/wiki/Blob_detection
    IIRC Nokia CV library have some feature points and motion flow algorithm, but they are not robust.
    Last edited by serg3d; 2009-03-31 at 05:51.

  9. #9
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    Re: compare 2 images

    Quote Originally Posted by abdelbakiguesmi View Post
    Thank you ,
    I want to compare the contents of two images to detect movement
    example :I have a reference image and I want to compare each time with another captured by the cam

    sorry for my bad English
    Have you tried this http://research.nokia.com/research/projects/nokiacv/. But i prefer to write my own motion detection algorithm.

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