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Re: Projector Calibration/ Lens Distortion

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  • Bhatt Himanshu
    ambient light is my BLACK Level. thanks to BENQ . my black is somewhat white. It says 13000:1 contrast ratio but for marketing only.. anyways graham CCD will
    Message 1 of 39 , May 22, 2013
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      ambient light is my BLACK Level. thanks to BENQ . my black is somewhat white. It says 13000:1 contrast ratio but for marketing only.. anyways graham CCD will make any difference in this situation??
      I am trying to find ND filters Locally as i read it is used in photography also..

      --- In diy_3d_printing_and_fabrication@yahoogroups.com, Graham Stabler <grezmos@...> wrote:
      >
      > You need to protect the sensor from ambient light, I would say it is just
      > washed out, may also need an ND filter to reduce the levels. I would also
      > not try and illuminate a single pixel but rather the whole sensor.
      >
      > Graham
      >
      >
      > On Wed, May 22, 2013 at 1:59 AM, Bhatt Himanshu <bhatthimanshu@...>wrote:
      >
      > > **
      > >
      > >
      > >
      > > Hello Guys,
      > > I tried CMOS Webcam With and without lens.
      > > here are the pictures of single pixel.
      > > i changed the focus of camera like we do in DLP.
      > >
      > >
      > > https://plus.google.com/photos/100257465905068566521/albums/5880595102721897089?authkey=CMvu7OS0pqHsSw
      > >
      > > i think without lens its not possible.....
      > > WIth lens there is lot of noise..
      > > for Diffuser i used butter paper(Tracing Paper)
      > >
      > > I think its very very difficult to do any automatic calculations..
      > > what you guys suggest??
      > > one more thing Google+ will show you enhanced picture . you have to press
      > > and hold enhanced button to view original images..
      > >
      > > Himanshu Bhatt
      > >
      > >
      > >
      >
    • Graham Stabler
      ... The reason I suggested a diffuser is because I was talking about converting a camera into a sensor so the image you get is actually an average of the
      Message 39 of 39 , May 23, 2013
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        On Wed, May 22, 2013 at 11:32 PM, Bhatt Himanshu <bhatthimanshu@...> wrote:

        @Graham
        I read about ND filters and i think i can get it from local camera shop. Do i need diffuser if i use ND filter/filters properly. 

        The reason I suggested a diffuser is because I was talking about converting a camera into a sensor so the "image" you get is actually an average of the light hitting the sensor. The idea of an ND filter is just to reduce the light levels though as I mention on another thread you can do this by projecting darker images anyway I think. 

        I want to make it clear that I am not suggesting trying to measure the output of a specific pixel on the projector but rather to get the average intensity over a fairly small area (because crappy webcam sensors are tiny) and then use a grid of these measurements to produce a correction which should be fairly smooth if the aberration is only caused by the optics.

        Cheers,

        Graham
         
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