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Image processing - count number of blobs

by Anonymous Monk
on Jan 08, 2013 at 22:35 UTC ( #1012346=perlquestion: print w/ replies, xml ) Need Help??
Anonymous Monk has asked for the wisdom of the Perl Monks concerning the following question:

I am presented with a number inside an image that I believe is generated by a captcha generator (securimage/phpcaptcha). I don't actually need to read the number represented in the image, but I do need to know when the magnitude changes. So if the current image contains "0.00005", I need to count the digits to find that it has six, so that when I get an image containing "0.09" and see that it contains only 3 digits, I can take the necessary action.

Here is an example image. I first tried using OCR (tesseract/gocr,/ocrad), but the captcha makes that too hard without first doing pre-processing, which might be a harder problem to solve (the text changes color and the background noise dots are randomly colored). So after doing some research it looks like Blob_detection is what I need to do and that it sounds like it might be an easier problem to solve. Except I can't find anybody doing anything similar in Perl. The only thing I can find is contained in much larger frameworks, like OpenCV or Matlab, etc., which would require using a different language and calling system on an external program.

Has something like this been done before in Perl?

Comment on Image processing - count number of blobs
Re: Image processing - count number of blobs
by Anonymous Monk on Jan 09, 2013 at 03:12 UTC
    keep walking spammer :)
      keep walking spammer :)
      Hey twit, if you read the OP I said I didn't need to actually read the number, which means this has nothing to do with solving captchas.

        Hey twit, if you read the OP I said I didn't need to actually read the number, which means this has nothing to do with solving captchas.

        Keep walking spammer

Re: Image processing - count number of blobs
by SuicideJunkie (Priest) on Jan 09, 2013 at 18:32 UTC

    If this really has nothing to do with solving captchas, I suggest asking the source to provide better images that don't look like captchas.

    If they expect you to comprehend the image using software, then they should provide an image that is not intentionally difficult to understand using software.

Re: Image processing - count number of blobs
by BrowserUk (Pope) on Jan 09, 2013 at 19:42 UTC

    Whether that example is a particularly easy one, but it cleans up very easily to the point where OCR might stand a chance, without doing anything fancy.

    Of course, if this is legit, you could point us at the source of the image and we could verify that what you are asking us to help you with isn't breaking any T&Cs.

    We could also obtain some more examples for testing our approaches to the problem.


    With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday'
    Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
    "Science is about questioning the status quo. Questioning authority".
    In the absence of evidence, opinion is indistinguishable from prejudice.
      Of course, if this is legit, you could point us at the source of the image and we could verify that what you are asking us to help you with isn't breaking any T&Cs.

      Of course this is against the TOS, just like any form of web scraping. The source site thinks that only humans should have any use of the data so make it hard to access, and I want to automate a process that involves the magnitude of the data.

      While everybody here was being so cynical and snooty, the Python community welcomed me and helped me convert the script to Python so I could easily interface with OpenCV. And another soul sees the light- not a better language per se, but a better community for sure.

        Of course this is against the TOS, just like any form of web scraping. The source site thinks that only humans should have any use of the data so make it hard to access, and I want to automate a process that involves the magnitude of the data.

        While everybody here was being so cynical and snooty, the Python community welcomed me and helped me convert the script to Python so I could easily interface with OpenCV. And another soul sees the light- not a better language per se, but a better community for sure.

        Got link?

Re: Image processing - count number of blobs
by Anonymous Monk on Jan 10, 2013 at 09:23 UTC

    which would require using a different language and calling system on an external program.

    Why do you think that ? Why is that a problem?

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