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Thread: Help on school project

  1. #1

    Default Help on school project

    Hi guys i really need your help,

    I am currently doing a school project on fingerprint recognition and I need to take the fingerprint images outdoor. The finger would be pressed on a glass and a camera below would take the image of that pressed finger. Now the problem here is that there is alot of reflection so I was thinking of substituting the glass with a polarizing filter. Where can I buy the cheapest filter for this purpose and how much would it cost? I saw one for $20 at yahoo auctions.


    Thank you for your time.

  2. #2

    Default Re: Help on school project

    Quote Originally Posted by lisarisa18 View Post
    Hi guys i really need your help,

    I am currently doing a school project on fingerprint recognition and I need to take the fingerprint images outdoor. The finger would be pressed on a glass and a camera below would take the image of that pressed finger. Now the problem here is that there is alot of reflection so I was thinking of substituting the glass with a polarizing filter. Where can I buy the cheapest filter for this purpose and how much would it cost? I saw one for $20 at yahoo auctions.


    Thank you for your time.
    Alternatively, you can do 1 of 2 things:

    1) Use non-reflective glass normally used for some photoframes. You can get this much cheaper than $20 I believe. Try those shops that do framing. They shld be able to sell you a small piece (Rememeber to get the edges smoothened to prevent cuts). If not, try Artfriend..may have something.

    2) Another way is to use a polarising filter on your camera lens. This will cost a bit more depending on your filter size and you tend to loose 2 to 3 f/stops depending on the price you pay for the filter.

    Good luck!

  3. #3

    Default Re: Help on school project

    non-reflective glass? Interesting.

    i don't know if I phrased my question correctly. But the issue here is that i do not want the sun light to get through the glass from the top down where the finger is. I only want my own light from the bottom up to make the finger visible to the camera below.

  4. #4

    Default Re: Help on school project

    Sorry for the double post. But in short, i just wanna make sure that my finger-capturing device takes images in a uniform manner where ever I may be. Outdoors or indoors.

  5. #5
    Moderator ortega's Avatar
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    Default Re: Help on school project

    why don't you just scan the fingers using a scanner?

    anyway wrong forum, thread moved

  6. #6

    Default Re: Help on school project

    Scanner? But I need something portable and within the scope of how a fingerprint scanner actually works, ive created this little box with the glass on top but it seems a filter used by professional cameras would do the job better at blocking out unwanted noise and light when i do it outdoors.

  7. #7
    Moderator ortega's Avatar
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    Default Re: Help on school project

    you can try to mod a small namecard scanner to suit your needs

    fixed focus (no worries about being out of focus)
    own light source (no worries about exposure)
    have a cover to block out external light

    think about it

  8. #8

    Default Re: Help on school project

    why dun you make the windows smaller?

    use the camera to take mulitply image when the finger scoll thru that windows, then combine all the image together.

    try use the same principal that a laptop finger scanner works.
    Last edited by conquer500; 10th December 2007 at 02:23 PM.

  9. #9

    Default Re: Help on school project

    Why dun make things simpler by making a cover? So the cover blocks off the ambient light. u noe, the concept of letterbox? but of course muz allow the hand to come out la.
    Chanxj
    my blog @ http://sgsnap.com

  10. #10
    Moderator catchlights's Avatar
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    Default Re: Help on school project

    you don't need PL filter. or non-reflective glass.

    all you need is to let the light come in 45 degree to the glass, and make a big black card with a hole to cover your camera except the lens.

    this set up is just like the copywork set up.



    Hope this help.
    Shoot to Live, Live to Shoot
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  11. #11

    Default Re: Help on school project

    Interesting 45 degrees idea.

    But I don't understand where ure telling me to put a black card. Why would I want to cover the camera?

    I have thought about using a cover to block the ambient light but its my last resort cause I don't want to add any form of bulkiness.

    Thanks so much for the help.

  12. #12

    Default Re: Help on school project

    To avoid anyone misunderstanding my issue ill be more detailed.

    This camera setup would involve taking a photograph with a webcam which is inside a box with a small hole cut at the top with a small piece of glass.

    I need 2 images taken. One when the finger is just about to press the glass. And the second is when the finger actually presses the glass.

    I need the both images to be as similar as possible when I take it outdoors,indoors, at night or in the morning.

    Colour would also be a very important feature I need. Cause the finger is usually pink when its not pressed and white when its pressed. I need these 2 colours to be as obvious to the computer as possible. Any tips on how to improve the colors in an image would also be very much appreciated.

  13. #13
    Moderator catchlights's Avatar
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    Default Re: Help on school project

    it is not an interesting idea,

    it is proven the standard set up and been using by many professional photographers, labs for copying documents and flat objects.

    using a black card with a hole just nice for the camera lens to go thru, the black card is shield the camera and yourself being reflected by the glass.
    Shoot to Live, Live to Shoot
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  14. #14

    Default Re: Help on school project

    Quote Originally Posted by lisarisa18 View Post
    To avoid anyone misunderstanding my issue ill be more detailed.

    This camera setup would involve taking a photograph with a webcam which is inside a box with a small hole cut at the top with a small piece of glass.

    I need 2 images taken. One when the finger is just about to press the glass. And the second is when the finger actually presses the glass.

    I need the both images to be as similar as possible when I take it outdoors,indoors, at night or in the morning.

    Colour would also be a very important feature I need. Cause the finger is usually pink when its not pressed and white when its pressed. I need these 2 colours to be as obvious to the computer as possible. Any tips on how to improve the colors in an image would also be very much appreciated.
    Not sure if I got this right, but I sense that rigging the box would be difficult, but the least of your problems, which would be:

    1) Seriously low res and inconsistent results from the webcam,

    2) Inconsistent luminence and colour (greatly due to the webcam factor) and also bcause light behaves differently, as you have identified, when going through a finger that is pressed and not pressed. Unless you adjust your lighting accordingly, and post-process it carefully, you are going to get variances in luminence, tone and colour.

    3) the only way to achieve "both images to be as similar as possible when I take it outdoors, indoors, at night or in the morning." is to put in place a highly controlled artificial light set-up where that light is the primary and over-riding source, aka, even if you stand in the middle of an open field at 12 noon, the artificial light is much stronger than the sun.

    Could I ask, exactly what is the intended output, aka, how do you need it used or presented in your project? Also, given your description of the box, I doubt if reflections would be the main concern depending on how and where you position it. I'm guessing that your project might be a bit ambitious, as usually these scanners are quite an example of precision engineering, and not cheap. Also, you would need a specialised soft-ware in place to 'illustrate' how the output of your scanner is used in finger-print recognition. I'm sure it's starting to get a bit complicated sounding becuase it is. I have a friend in the Netherlands who writes programmes specifically for electronic microscopic forensics and research/data gathering work, aka, ballistics matching, lining-up of wounds, comparative and contrast analysis etc, and he tells me that the equipment involved is fairly complex.

    Have you considered Ortega's suggestion of a small name-card scanner?
    Last edited by Dream Merchant; 11th December 2007 at 08:12 PM.

  15. #15

    Default Re: Help on school project

    i agree with dream merchant. It is virtually impossible to have any consistency with a web cam. for a simple reason there's not enough res. And colours aren't exactly accurate on that small little ccd...

    Is the purpose of this project is for your team to understand "how" a finger sensor works? or how the sensor tell the difference of the finger print?

    If your lecturers expect you to have a working model of a fingerprint analyzer... i think he/she needs to give u guys more fundings...

    btw... can u ink the fingers... that will help make it clearer for ur webcam to see the prints... with artifical lights or natural lights coming thru the glass should give some nice contrastly prints
    P&S: Sony U20, Pana-leica FZ5, Canon S90, Pana DMC-T3
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  16. #16

    Default Re: Help on school project

    Im not too enthusiastic about the scanner cause it probably cost quite abit. Where would you guys suggest I go have a look at the scanner at the cheapest price and roughly how much would it cost?

  17. #17

    Default Re: Help on school project

    can just buy a fingerprint sensor? i think thats alot cheaper... about SGD 70-80...

    i don't know about scanner price... haven't been using them for almost a decade already...
    P&S: Sony U20, Pana-leica FZ5, Canon S90, Pana DMC-T3
    SLR: Nikkor F60, Oly E-510, Oly E-5

  18. #18

    Default Re: Help on school project

    I'm sorry I have no idea.

    Why not check with Ortega?

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