[cpia] The Sensor defined Resolution Mode
Tobias Gogolin
tobias@ing.ens.uabc.mx
Mon, 17 Jul 2000 13:24:56 -0700
Ok forgive
I just found the ST Vision site up again
and the sensor detail
And it is really only a 100k sensor
So I guess it is pretty much used to capacity ?
cheers
Tobias
----- Original Message -----
From: Tobias Gogolin <tobias@ing.ens.uabc.mx>
To: Peter Pregler <Peter_Pregler@email.com>; <cpia@risc.uni-linz.ac.at>
Sent: Monday, July 17, 2000 12:18
Subject: Re: [cpia] The Sensor defined Resolution Mode
> 640 x 480
> > > The informed may know it is the real mode the highest supported by
> hardware
> > > ...
> >
> > I am informed and I can tell you that the CPiA hardware we have
> > written the drivers for cannot go 640x480.
>
> Yes sure and that is why Logitech doesnt want to give out the specs of
theyr
> new Interface Mode
> Point is
>
> Is the sensor used to its fullest potential ?
> If it is a 300 k pixel sensor its not
> But every image ever captured with a cpia camera still contains the higher
> resolution data :
>
> Let me Quote some of the comunication I previously led with Jan
> :============================================================
> Looking about what cameras are available out there I think
> I got a usefull step in understanding more about how these cameras really
> work ...
>
> One Manufacturer (Ezcam USB webcam )
> http://www.ezonics.com/dual.html
> was advertizing 320 000 pixels cmos sensor
> and resolutions of
>
> 640 x 480 = 307200 That mapes pixel to pixel
> However color is needed
> 353 x 288 = 101376
> I asume there is a filter mask either RGB or CMY
> So in this mode 3 proximate sensors with individual colors are combined
> to give one real color aproximation of the light that hits the 3 sensors
> required
> ---------------------------
> I believe the actual sensor is pretty much identical with the Logitech!
> Logitech is not relaesing its specs because they are more or less the same
> as others
> However they figured out - what I am trying to share with you now:
> > >640 x 480 = 307200 That mapes pixel to pixel
> ...
> > >In the highest resolution mode the filter is still in place
> ...
> > >Therefore in this mode the camera must try to extract the luminance
from
> > >each pixel
> Lets Asume
> Pr = red filtered pixel
> Pg = green
> Pb = blue
>
> Pr(Pg, Pb) is really also going active with white and grays to black
> therefore each pixel contains luminance information as well
>
> after the capture data is available in a raster with
> 352 x 288 x 3 x 8 Bit color values
>
> We will need some insight of the allignment of the filter masks
> (you may want to put one under the Microscope :)
>
> If you take a lens and look at a delta screen mask of a color Tv every Red
> is surounded with 3 Pairs of GB
> same for Green and Blue
>
> Because I am concerned sensor makers may have found limitations in
> chiplayout to rectangular patterns
> its probably more likely chances are the filter is simply aligned
> RGBRGBRGBRGRB
> RGBRGBRGBRGRB
> RGBRGBRGBRGRB
> But that would be pretty ineficient especially for what I am saying could
be
> done (or is done by logitech
> Maybe
> RGBRGBRGBRGRB
> BRGBRGBRGBRGRB
> GBRGBRGBRGRB
>
> RG
> B
>
> GB
> R
>
> BR
> G
>
> every block of 3 pixels is complete in itself
>
> if we could find out about the physical layout in rows and columns of the
> sensor
> or maybe there is even a spec about the filtered sensor
>
> -------------------------
>
> Per software it is possible (the logitech implementation proves (not
without
> little failures)) to remap the aquired 352 x 288 data onto a 640 x 480 map
>
> Its serious math to do it well :
> one would best distribute the color info on an area around the location of
> each filterd sensor (in the expanded file) - then one would go and see how
> much deviation from the low pass color area one has in an individual
sensor
> cell and create a luminace vector out of the local deviation (cosidering
> filter color and low pass area color)(and initialy put that in a seperate
> map) when done combine the maps and have a full color 640 x 480 output ?
>
> Some examples:
> http://ultra.ens.uabc.mx/lvp/visdat/ciaA0473.jpg
> see the / slanted line on the left where high definition light and color
> changes get misrepresented into colorful ladders
> - clear evidence that they are using the technology I am describing
>
> http://ultra.ens.uabc.mx/lvp/visdat/d109102851430.jpg
> see how great it works to get the real detail out of low colorchange
images
> look at the masoned stonewall lines. Again a high contrast /(slant) causes
> the seperationfaults
>
> http://vidar.ens.uabc.mx/lvp/visdat/d001902721500.jpg
> in comparison the low format analizis causes grainy
> and unaliased looking effects sometimes
> ladders apear not to have the color seperation fault
> However take the time and load the image with a zoomtool
> and look at the balcony and the luminance jagies those actually
> contain data that when properly layed out becomes valuable detail
>
> ==========================================================
>
> Anyhow I am glad to hear that I am talking to the developers themselve :)
>
> > I am informed and I can tell you that the CPiA hardware we have
> > written the drivers for
>
> I am looking forward to work with you on implementing the higher
Resolution
> Mode !
>
> If you consider It enough of a challenge that is ...
>
> cheers
>
> Tobias
>
>
> ----- Original Message -----
> From: Peter Pregler <Peter_Pregler@email.com>
> To: Tobias Gogolin <tgogolin@web.de>; <cpia@risc.uni-linz.ac.at>
> Sent: Monday, July 17, 2000 01:45
> Subject: Re: [cpia] The Sensor defined Resolution Mode
>
>
> > On Mon, Jul 17, 2000 at 10:35:01AM +0200, Peter Pregler wrote:
> > >
> > > /* Is it a CPiA? */
> > > if (!((udev->descriptor.idVendor == 0x0553 &&
> > > udev->descriptor.idProduct == 0x0002) ||
> > > (udev->descriptor.idVendor == 0x0813 &&
> > > udev->descriptor.idProduct == 0x0001))) /* GA 04/14/00 */
> > > return NULL;
> > >
> > > The first one is a normal CPiA such as the Creative Webcam II, the
> > > second one is the Barbycam. In any case the highest resolution the
> > > chip can do is CIF.
> >
> > Ahem, the second one is the Intel Play QX3 Microscope. Silly me.
> >
> > -Peter
> >
> > --
> > I will not waste chalk. --Bart Simpson at the blackboard
> > --------------------------------------------------------
> > Email: Peter_Pregler@email.com
> > WWW: http://www.risc.uni-linz.ac.at/people/ppregler
> > ICQ: 61011460
> >
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>
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