Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
10-09-2010, 04:38 AM   #31
Site Supporter




Join Date: Mar 2009
Location: Gladys, Virginia
Photos: Gallery
Posts: 16,243
QuoteOriginally posted by Eruditass Quote
I meant equivalent to RAW. If RAW has that level of NR, that's ridiculous.
No one knows how much noise reduction is actually applied to RAW on any given camera. The K20 supposedly had some noise reduction applied even to RAW files starting at iso 1600, while the K7 allowed you to turn it off all the way up to iso 3200, but is off really off? People like Gordon B Good attempt to figure that out and feel like most companies apply some NR even to RAW files at high iso. This can be used to a certain extent to manipulate Dxo scores.

10-09-2010, 07:32 AM   #32
Veteran Member
falconeye's Avatar

Join Date: Jan 2008
Location: Munich, Alps, Germany
Photos: Gallery
Posts: 6,863
There is NR and NR.

What is shown in the Sony chart mostly describes normal engineering. The analog noise reduction is interesting. But may be nothing but a higher gain in the charge-voltage conversion (with higher ISO) combined with some clipping. And the RAW NR done on chip may be hot pixel treatment and fixed pattern noise reduction which must always be applied to sensors. It may also involve binning of dark pixels which is where Sony seems to trick a bit. Or a weighted averaging of pixels beyond some ISO threshold like Pentax does.

Nevertheless, that's all playing kindergarden games. Real NR is a sophisticated algorithm based on information theory where the most likely signal prior to noise is reconstructed (it is clear that the original image is not the most likely signal because is has too many high spatial frequency terms). I've written one such algorithm myself. It's doable in the camera firmware but most in-camera implementations are poor, i.e., they reduce both, noise AND signal (IMHO, Nikon has the only fair in-camera implementation today). This is where RAW converters and NR software come into play. The JPG settings for NR almost only apply to this last stage of NR and "off" means a setting where the reduction of the signal isn't so obvious.
10-09-2010, 07:41 AM   #33
Pentaxian




Join Date: Jun 2009
Location: GMT +10
Photos: Albums
Posts: 10,843
This extra diagram may help clarify some of the NR processing in an Exmor sensor.

10-09-2010, 08:42 AM   #34
Veteran Member
falconeye's Avatar

Join Date: Jan 2008
Location: Munich, Alps, Germany
Photos: Gallery
Posts: 6,863
QuoteOriginally posted by rawr Quote
This extra diagram may help clarify some of the NR processing in an Exmor sensor.
Thanks. The magic and new word in this diagram is CDS. It is used in conjunction with "noise cancelling" and "sampling system". Therefore, it is clear what they mean: Correlated Double Sampling.

This is common engineering practice indeed. It isn't noise reduction in photography terms. It's removal of an unwanted extra signal caused by non-linearities. It is more like a dark frame subtraction than conventional NR. To do this on-chip is perfect and won't take away from the signal.

10-11-2010, 04:29 PM   #35
Site Supporter
jpzk's Avatar

Join Date: Jan 2009
Location: Québec
Photos: Gallery | Albums
Posts: 7,258
QuoteOriginally posted by Fl_Gulfer Quote
If you were all quiter when takeing pictures you wouldn't need all that noise reduction....
"Needing" NR doesn't equate "Discussing" NR !

JP
Reply

Bookmarks
  • Submit Thread to Facebook Facebook
  • Submit Thread to Twitter Twitter
  • Submit Thread to Digg Digg
Tags - Make this thread easier to find by adding keywords to it!
focus, jpeg, k-r, lenses, pentax news, pentax rumors
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
K-x jpeg vs raw high iso question barondla Pentax DSLR Discussion 6 08-12-2010 02:39 PM
Are high ISO considerations based on jpeg or raw? justtakingpics Pentax DSLR Discussion 16 06-04-2010 08:32 AM
K-7 high ISO vs K20D high ISO supa007 Pentax DSLR Discussion 72 05-10-2010 04:24 PM
Any more K-m direct Jpeg samples? RiceHigh Pentax DSLR Discussion 0 10-21-2008 07:59 AM
Some K10D Jpeg samples ... Lisa_Bonami Pentax DSLR Discussion 13 12-29-2006 09:30 AM



All times are GMT -7. The time now is 08:50 PM. | See also: NikonForums.com, CanonForums.com part of our network of photo forums!
  • Red (Default)
  • Green
  • Gray
  • Dark
  • Dark Yellow
  • Dark Blue
  • Old Red
  • Old Green
  • Old Gray
  • Dial-Up Style
Hello! It's great to see you back on the forum! Have you considered joining the community?
register
Creating a FREE ACCOUNT takes under a minute, removes ads, and lets you post! [Dismiss]
Top