Nagging questions

Just some random, mostly resolution-related questions. I fully accept
that the questions themselves may be misguided, so feel free to interpret.

Chip size, noise and other stuff.

All other things being equal, will a larger sensor have more noise? I
ask this for two, interrelated reasons, the first of which is that I see
discussions of the end of the Megapixel wars for APS-C sensor due to the
loss of image quality with higher pixel pitch. The second is that I have
recently seen some pretty good images from a Canon G10 which has a much
higher pixel pitch albeit on a much smaller chip.

Actual resolution increase with higher pixel pitch.

It certainly seems that the G10 has much higher resolution than my 5D
(but certainly not better image quality) considering the pixel
pitch/sensor size. What actual resolution increase could I expect with
that kind of pixel pitch on an APS-C or FF/35mm sensor? Is there some
formula that describes the diminishing resolution gains due to added noise?

Size of pixel/photosite where resolution increase would not equal
additional pixels.

Is there a certain way in which noise is related to the size of the
individual photosite? Or is that dependent upon other factors that can
be addressed through better engineering/manufacture of the sensor?

Conversion of Bayer pattern only affect colors of image.

Finally, do the algorithms used to convert the output of a Bayer-type
sensor independently process luminance and color information? I guess
that would be, does the algorithm produce color and luminance
information independently of each other such that a grayscale value
could be produced for each pixel without using information collected at
more than one photosite?

Eric Miller
www.dyesscreek.com

Eric Miller wrote:
> Just some random, mostly resolution-related questions. I fully accept
> that the questions themselves may be misguided, so feel free to interpret.
>
> Chip size, noise and other stuff.
>
> All other things being equal, will a larger sensor have more noise? I
> ask this for two, interrelated reasons, the first of which is that I see
> discussions of the end of the Megapixel wars for APS-C sensor due to the
> loss of image quality with higher pixel pitch. The second is that I have
> recently seen some pretty good images from a Canon G10 which has a much
> higher pixel pitch albeit on a much smaller chip.

Basically it is the sensor "site size" that has the most affect on
signal but noise does not vary that much. Of course with less signal
the noise becomes more important.

Canon has developed remarkable noise reduction s/w as well, so they can
make less than optimal hardware look very good.

>
> Actual resolution increase with higher pixel pitch.

Lens and anti-alias filter limited.

> It certainly seems that the G10 has much higher resolution than my 5D
> (but certainly not better image quality) considering the pixel
> pitch/sensor size. What actual resolution increase could I expect with
> that kind of pixel pitch on an APS-C or FF/35mm sensor? Is there some
> formula that describes the diminishing resolution gains due to added noise?
>
> Size of pixel/photosite where resolution increase would not equal
> additional pixels.
>
> Is there a certain way in which noise is related to the size of the
> individual photosite? Or is that dependent upon other factors that can
> be addressed through better engineering/manufacture of the sensor?

Yes. Roughly speaking noise does not change much with site size; but
signal goes up as the site size increases thereby increasing S/N.

>
> Conversion of Bayer pattern only affect colors of image.
>
> Finally, do the algorithms used to convert the output of a Bayer-type
> sensor independently process luminance and color information? I guess
> that would be, does the algorithm produce color and luminance
> information independently of each other such that a grayscale value
> could be produced for each pixel without using information collected at
> more than one photosite?

Good question.