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11-22-2009, 03:52 AM   #31
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Yes, it is rather interesting.
The thing with sensors is that it was hard and uneconomical to manufacture them such way, but such "correct" designs have existed for scientific and other high end uses already before. For CCD's as well.
Sony has gone further by developing such manufacturing process where they can make large quantities of such sensors with constant parameters, previously only limited runs were possible.
So they have significantly reduced the costs of such sensors, allowing for use in consumer products.

I wonder how such backlit CMOS stands against backlit CCD.

Another thing to think about is, since the circuitry is not any more in front of the sensor, you don't have to use extremely thin wires (to allow light to pass) which generate heat and noise. This allows the electronics to be of rather free design, so they can be optimized for best performance.

But for the reflecting thing, most sensors are designed with a photo diode that absorbs most of the visible wavelengths before it penetrates.
I'd be more inclined to think that there should be something done with the colour filters, which currently are passive and "wastes" all other light but the colour they transmit.

One step closer to better performance would be the use of filters with wider, overlapping pass bands, producing non RGB colour space readout which is later converted to RGB colour.
I believe there were some 4 colour filters:
Sony DSC-F828 Review: 1. Introduction: Digital Photography Review
But it seems that the colours are chosen to expand the colour gamut instead of light transmittance.

Ultimate solution, of course would be a system that splits/sorts the colours instead of removing unwanted parts of spectrum (colours).

11-22-2009, 10:19 AM   #32
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QuoteOriginally posted by tr13 Quote
Unfortunately RAW data can be much more distant from adc readout then JPEG from RAW renderer result.
What measure of "distance" are you considering that could *possibly* yield this result? Feel free to be specific - I have degrees in both mathematics and computer science. But I am quite confident you won't be able to provide any such metric. I'm assumign you've been looking very hard at the things that are done betwene ADC readout and the writing of the RAW data, an are aware of whatever differences there are, but haven't looked at all at JPEG rendering, and have no idea just how many orders of magnitude more distant that is.

FWIW, I've stayed out of this, but I agree with the other posters - with the zillions of variables involved, there is absolutely no way that one can possibly read the results of such as a test as being about CCD versus CMOS. There are far too many uncontrolled variables. And I don't think it's *possible* to control them. Eben if you managed to find two camera that were identical in all respects except the sensor, and one was CCD but the other CMOS, all you'd really be seeing is the difference between that *particular* CCD and that *particular* CMOS. Which could be as much a factor of the specific color filters used as the underlying technology.
11-22-2009, 03:34 PM   #33
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Marc, I believe that your post is just result of misunderstanding.
I really did not want to perform scientific lab test with general conclusion about CCD vs CMOS. If you want to do this, we can make comparison of early post-ADC RAW data between K10D and K20D or Kx.
And my quote in your post is correct, as RAW to JPEG algorithms in camera and in renderer are pretty similar at many stages. But ADC to RAW can be real different in different cameras.
11-22-2009, 05:42 PM   #34
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From a practical point of view an interesting difference could be one that is not reversible or processable in any convenient way (Casts unremovable by simple white balance adjustments, colour components or brightnes graduations that are lost independantly of colour space, format or rendering scheme used).

Which one of the mentioned do you experience most with that rose picture?

I'd say it feels like the GX20 one has "less colours" - like "monochromatized" - colour space has been compressed in fewer, more satureted and purer colours, when the panasonic has more wider range of actual colours instead of pure reds and greens.

On my monitor the brightness range seems to be well rendered in both shots (no clipped areas), as far as you can tell with that JPEG quality (try posting them in flicker or similar place, with lower compression).


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