Hey dude,
I've notice that you seems to know a bit more about noise than many here. Studied imaging in EEE? Thus, can I seek your advise?
I'm actually thinking of getting either the pana FZ7 or the canon S3. If I can refer you to the noise examples of the city night shot comparing ISO in
http://www.dcresource.com/ review for FZ7 and S3.
My unexpert eyes tell me that the FZ7 has got lots of color noise(eg iso400) and the S3 lots of grainy noise(lots! especially ISO400). My question is which of these noise is of a lesser devil?
Thanks in advance for sharing...!!!
A fellow NTU :bsmilie:
Part of my reply to him is here..
just realise that the new review of the S3 is up. Just went to see see.. Since there wasn't any studio shot done for the FZ7, I can't compare against the studio shot. The studio shot images shouldn't be taken into account due to the unnatural good lighting that studio strobes offer.
Given the noise removal stuff I've learnt so far, grain noise is easier remove. That's the textbook answer. However, that's given that peak values are far and few between. For this case, the S3 has simply too much grain IMHO for effective noise removal.
Colour noise is quite easily removed (VERY VERY effectively) with PS CS2, but you may end up removing some of the colours that's supposed to be there. From then on it's a matter of skill (use of layer mask etc).
facts:
1) FZ7 IS sharper. You can tell by the building outlines. S3 produces hazy lines. Thus,the lens produces soft.
2) at ISO200/ISO400, especially at ISO400 onwards, the noise is so horrible that the edges of the buildings are sorta gone..
3) for basic noise removal, in layman's terms, it's a guessing game. a value is guessed/calculated for each pixel from the surrounding block of maybe 5 x 5 pixels.
4) It's hard to do accurate guessing especially since possibly 1/2 the neighbours in a 5x5 neighbourhood are also noise pixels.
5) In cases where the edges are so diffused, it'll be hard for any noise removal program/algorithm to guess/calculate the correct value for any pixel. (i.e determine if the pixel should be dark or light). You may most prob end up with edges which you cannot USM even.
6) for trying to remove the noise frequency component.. There's nothing periodic about this to remove, at least to me. I'm only an undergraduate. There are possibly some magical ways which I've not learnt about yet. AFAIK, the noise is of a random nature. This won't work out.
Which gives a better result after noise reduction? Which gives less image degradtion? Which is easier to do? You judge for yourself, least you say I'm biased towards one or another brand. If you can come out with better processed images based on the ISO400 crop given at dcresource, do show. I'd wanna learn how to do it.
After simple noise processing, no sharpening done at all:
FZ7 before + after(colour noise removal only)
S3 before + after (remove grain in lab colour, + colour noise removal)
Cheers