Re: [Rtftr-devel] some ray of hope after using vigra

[lakesh <lak...@gm...>]

Hi Abhishek,
I think you deleted the matlab and kepenekci_part2 directories during your
previous commits. I am adding them again ok.

On Sat, Dec 20, 2008 at 9:19 PM, lakesh <lak...@gm...> wrote:

> Also about sigma most of the papers they have taken 2pi like us. But this
> is totally arbitrary as said by one of the people in the groups
>
>
> On Sat, Dec 20, 2008 at 9:15 PM, lakesh <lak...@gm...> wrote:
>
>> Hi Abhishek,
>>
>> I was tuning the parameters of the Gabor filters and I think I got some
>> improvements. I changed the window size and the threshold and some other
>> parameters. There is slight improvement; however we can tune the parameters
>> to any thing we want that is we can overfit it to a specific image. Also
>> other thing is that we don't need to get the high energy points to the
>> specific locations like  eyes,nose mouth etc. I got some papers where they
>> have used adaboost for feature selection and the features are located at
>> random locations like us. Also in most of the papers they have taken
>> frequency as sqrt(2). The ebgm paper has also taken the same frequency. Also
>> I think while comparing the responses of the images to get the feature point
>> we should use directly the magnitude. I mean when we shift through the image
>> using the window of size WxW to compare the results, we should use the
>> magnitude of the response for the comparison and not directly the complex
>> numbers. I tried to compare the complex number and it considers only the
>> real part while doing the comparison. So I think it is not the correct way
>> to compare. Though in Kepenekci  it seems like they have directly compared
>> the complex numbers, I think we should use the magnitude values directly.
>>
>> Lets sit and discuss the parameter selection when you finish the C++
>> implementation.
>> Currently I am laying my hands with everything I can  find and checking
>> the results.
>>
>>
>>
>> On Sat, Dec 20, 2008 at 8:46 PM, Abhishek Dutta <the...@gm...
>> > wrote:
>>
>>> Hi lakesh,
>>> I decided to use "vigra<http://kogs-www.informatik.uni-hamburg.de/%7Ekoethe/vigra/>"
>>> library instead of GSL. GSL was not sufficient and did not fulfill all our
>>> requirements.
>>>
>>> "vigra" allows to generate gabor filter family by just supplying the no.
>>> of orientations, scale and center frequency. According to the "vigra"
>>> documentation, center frequency should not exceed 0.375. However, I was
>>> using sqrt(2) = 1.414 as frequency in matlab implementation. Moreover, it
>>> selects the best gaussian function (the sigma that we needed to supply)
>>> based on a mathematical formula (that I didn't understand). The output (at
>>> image size 128x128) looks good. But this does not assure better final
>>> results. I will update you with final results after I complete the code to
>>> compute feature vectors.
>>>
>>> bye
>>>
>>> --
>>> Abhishek
>>> http://adutta.np.googlepages.com
>>>
>>
>>
>>
>> --
>> Have a nice day
>>
>
>
>
> --
> Have a nice day
>



-- 
Have a nice day