How quality of images in DSLRs depends on sensor size & effective pixel (and price)?

[kakou]

There's one catch with that.

Bayer image can be 100% correctly demosaiced only when image spatial frequency (is that right term?) is less than Nyquist frequency for every single color channel (and there is no noise present). This approcah involves using AA filter (lowpass for spatial frequencies) and killing pixel-level details (high frequencies) with that.

It only needs to be less than the sensor's Nyquist frequency, not for each individual colour, and nothing is ever 100% exact anyway.

Of course there exist algorithms, decoding/interpolating Bayer images, containing higher spatial frequencies too. This is usable in MF and other bigger sensor cameras without AA filter, where introduced pixel-level artifacts and aliasing are almost invisible due to the big pixel count.

Higher spatial frequencies need a higher resolution sensor. Medium format is now at 60 megapixels. It's also not cheap.

But I've yet to see universal foolproof algorithm to demosaic such 'aliasing affected' Bayer images. Some raw decoders allow change algorithms and/or adjust their parameters - for different kind of images demosaicing results differ greatly.

There isn't a single algorithm for anything. The better Bayer algorithms are adaptive, which is a good thing.

 

[bonku]

Thank you all for such valuable information. It'll help me personally to learn a bit more about basics of digital photography.

 

[uncle]

agree

 

[bonku]

I just purchased Canon 7D. Besides many other excellent features, Color reproduction in that camera is much better than Sigma SD14 (at least to me). Pics taken at higher ISO like 1000 or 2000 is not an issue at all, while SD14 have noticeable impact for ISO equals or more than 800.
I was wondering how living animals see pics and color around. Then I realized that it’s more like a Bayer sensor (not a foveon type 3 layer mechanism) and that monolayer mechanism has preferred through millions of years of evolution/selection.

 

[Arvo]

Congrats for your new camera!
Now waiting comparison pics - and please try to get *best* off the both cameras (not high ISO for SD14 for example). Because posted images should be enough small, at least resolution advantages of 7D will be void

 

[bonku]

Thanks Arvo.
I have sold my SD14 and all my Sigma mount lenses :sad:.
Anyway, I will dig out some old pics taken with SD14 and then post a new pic with Canon 7D.

 

[bonku]

Here it is.
First Picture was taken by SD14 (Sigma 18-200mm, ISO- 200, Av-3.2 Tv-1/60, WB: Unknown).


The second picture is by Canon 7D (Tamron 18-270mm, ISO-1200, WB: Tungstain, Av-5.6, Tv- 1/15).
Both the pictures were taken in the same room, under same lighting condition (of the same child).