Digital BW, The Print

Mark Savoia wrote:
> Did you download the high res image? Is that a real sample of what  
> the chip can do or is it just the storytellers shot? It is very noisy.
> Mark
> 
> On Dec 12, 2005, at 11:35 AM, Ernst Dinkla wrote:
> 
>> Better dynamic range in sensors is more promising and may not
>> be that long away:
>>
>> http://www.rochester.edu/news/show.php?id=2367
>>
>>                     --
>>            Ernst Dinkla

Mark,

Don't know. Still downloading that image :-) Doubt they put a 
file like that on the page without further information how it 
was made.

There's an interesting thread on the news forum of dpreview on 
this subject (but sadly enough a non topic thread running 
through it). An excerpt of that thread:

Just Looking wrote:
 > Pixim has been doing in-pixel A-to-D conversion for years 
using a
 > Delta-Sigma scheme. How is this different?

Different company, different packaging. Looks like Pixim is 
actually further along, because they already have commercial 
products.

Other than that - very similar, except for this modified 
spacing of pixels that's supposed to favor jpeg conversion (I 
wonder if it affects the cost of the Bayer and AA filters for 
this sensor), so good find there.

Pixim's products advertise "512X Dynamic Range" - that's 9 
stops, the sensor is made for video cameras:
http://www.prosecuritys.com/gsdct-ps615xt.html

Actually, they recently issued a press release about a new 
chipset a few months ago - but again, this is a video chip, 
doesn't target still photography:
http://www.pixim.com/html/press_release_050927.htm

For those who (like me) needed more information about 
Delta-Sigma conversion, here's a Wikipedia article (it gets 
pretty involved though):
http://en.wikipedia.org/wiki/Delta-sigma_modulation

"The principle of the sigma-delta architecture is to make 
rough evaluations of the signal, to measure the error, 
integrate it and then compensate for that error."
It also has a link to java-based simulation:

http://www.analog.com/... 
.../interactiveTools/sdtutorial/sdtutorial.html

End of quote.

So there has been experience with a similar system already.

Ernst

-- 

                    --
           Ernst Dinkla


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