Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
08-06-2010, 01:19 PM   #1
Veteran Member




Join Date: Apr 2009
Location: New York
Posts: 328
Lowering image size to lower ISO noise?

I'm curious about something. Since high ISO noise increases as the pixel density gets higher, do you think that lowering the image size on the K7 from 14mp to 10 will help lower the noise?

Everyone I know that has/had a K200 talked about the smooth noise patterns because of its 10mp sensor. Also, the K100 did very well because it was 6. But does a 14mp sensor literally act like 10 when you lower it or does it just emulate it? Does the pixel density actually change?

I know I'm either going to do larger print shots or low light shots, never both. So I see no loss for me by dropping to 10MP at those occasions, especially when there'll be no IQ loss from the change.

I hope this made sense.

08-06-2010, 01:22 PM   #2
Veteran Member
future_retro's Avatar

Join Date: Jun 2010
Location: Western Washington
Posts: 572
I'm honestly just guessing because I don't know for sure, but I think that no matter what JPEG settings you use, it captures a full 14mp RAW image and then depending on your JPEG settings, dumps a certain amount of information from that 14 MP RAW and then saves it as a JPEG accordingly. I don't think the JPEG settings are capture settings, but saving settings
08-06-2010, 01:40 PM   #3
Veteran Member
Jasvox's Avatar

Join Date: Oct 2007
Location: Melbourne, Australia
Posts: 3,110
I theorized about this (as have many) in the past and according to my readings and findings, the short answer is NO.

Here's a good read and explanation, but there are many other examples if you search and read.

Downsampling to reduce noise, but by how much?: dpreview.com Editorial blog: Digital Photography Review

Jason
08-06-2010, 03:40 PM   #4
Pentaxian
jimH's Avatar

Join Date: Apr 2009
Location: South Central Nebraska - USA
Photos: Gallery | Albums
Posts: 1,422
I don't know about this, I've got a 10 mp k10 and on under exposed shots the noise is very bad.

08-06-2010, 03:57 PM   #5
Pentaxian
JohnBee's Avatar

Join Date: Sep 2008
Location: front of computer
Posts: 4,620
QuoteOriginally posted by jboyde Quote
I'm curious about something. Since high ISO noise increases as the pixel density gets higher, do you think that lowering the image size on the K7 from 14mp to 10 will help lower the noise?

I know I'm either going to do larger print shots or low light shots, never both. So I see no loss for me by dropping to 10MP at those occasions, especially when there'll be no IQ loss from the change.
It's a common thought I think
Because its come-up a umber of times over the ages.
Unfortunately, it doesn't quite work out this way and the results are less than beneficial.

The good news is that you can post process a file(full size) and reduce your final results a bit to help tighten things up(sharpness and artifacts).

However... since you mentioned high ISO and large format, my advice would be to take advantage of the K-7's faster FPS to achieve super resolution. Okay, super resolution is not actually a term(per say), but more of a technical term used by a company called PhotoAcute.

But the good news is that the software and your camera can achieve both cleaner ISO and higher resolutions simultaneously. As seen bellow:

ISO noise reduction:


Resolution enhancement:


Take Better Photos, reduce noise, increase quality and resolution of digital photographs. Leading superresolution technology.

PS. I've used this to create 3 -2.5x6' wall images for our living room.

Last edited by JohnBee; 08-06-2010 at 10:37 PM.
08-06-2010, 05:50 PM   #6
Site Supporter
jpzk's Avatar

Join Date: Jan 2009
Location: Québec
Photos: Gallery | Albums
Posts: 7,258
QuoteOriginally posted by JohnBee Quote
It's a common thought I think
Because its come-up a umber of times over the ages.
Unfortunately, it doesn't quite work out this way and the results are less than beneficial.

The good news is that you can post process a file(full size) and reduce your final results a bit to help tighten things up(sharpness and artifacts).

However... since you mentioned high ISO and large format, my advice would be to take advantage of the K-7's faster FPS to achieve super resolution. Okay, super resolution is not actually a term(per say), but more of a technical term used by a company called PhotoAcute.

But the good news is that the software and your camera can achieve both cleaner ISO and higher resolutions simultaneously. As seen bellow:

ISO noise reduction:


Resolution enhancement:


PS. I've used this to create 3 - 4x6' wall images for our living room.
John,

This seems a bit awkward: how can any algorithm calculate and align pictures taken in continuous mode unless you've shot several bracketed pics; unless it's me not understanding the process, I can see a software doing this but with bracketed shots while the cam is on tripod so that everyting will be almost perfectly "aligned" to start with.
So, if I was to take several shots of an oncoming bird, for instance, I can hardly understand how the software would extract info from several pics taken that way and "make one good pic" !?
Sorry about barging in on your thread Jboyde, but as usual I am not quite understanding this process here esplained by John.

JP
08-06-2010, 06:08 PM   #7
Pentaxian
JohnBee's Avatar

Join Date: Sep 2008
Location: front of computer
Posts: 4,620
QuoteOriginally posted by jpzk Quote
So, if I was to take several shots of an oncoming bird, for instance, I can hardly understand how the software would extract info from several pics taken that way and "make one good pic" !?
You have indeed exposed one of the limitations of this technology. Which works well enough handheld, however... it has its limits too, and your example is one of those instances.

Having said that, for what its worth, the software does work quite well within the confined of its limits. I have taken a number of shots(handheld) which turned out okay enough with regards to moving tree's, waves etc etc.

TBH. I never really pushed the software to see how far it could deal with movement, but I have no doubts that it has its fair share of issues in this sens also.

Having said that, I think the software works best with scenery's and tripod shooting. Which turns out to be pretty impressive considering it almost doubles the effective resolution in the process.
08-06-2010, 10:30 PM   #8
Veteran Member
mysticcowboy's Avatar

Join Date: Apr 2009
Location: port townsend, wa
Photos: Albums
Posts: 968
I have to say that I've been impressed with the results I've gotten with PhotoAcute, handholding for still subjects. No, it won't work if the subject is moving quickly. It will align multiple frames much better than Photoshop. As a matter of fact, PhotoAcute uses the slight differences in positon in its sharpening algorithms.

Unfortunately, most of my high ISO photos are handheld and of people, who have a bad habit of moving. ;-) If I can use a tripod, I often don't need the ISO bump.

To the original question. If you shoot full size then reduce the image size in post, much of the high ISO noise will be processed out in the reduction with any software. PhotoAcute isn't needed for that.

08-07-2010, 07:42 AM   #9
Veteran Member




Join Date: Dec 2007
Posts: 923
Going from 14MP to 10MP does not produce sufficient compression to make much difference in visible noise.

Going down to 1 MP - still good enough to view full screen - does do the trick. The averaging of values from adjacent pixels involved in shrinking the photo helps remove a lot of high-frequency noise, but any large blotches of noise will still be visible.

Even shots from P&S cameras with mediocre High-ISO performance can look presentable when you shrink it down several X.
08-07-2010, 08:30 AM   #10
Veteran Member
RioRico's Avatar

Join Date: Jun 2008
Location: Limbo, California
Posts: 11,264
QuoteOriginally posted by kittykat46 Quote
Even shots from P&S cameras with mediocre High-ISO performance can look presentable when you shrink it down several X.
Almost everything looks good if it's small enough. And printed on textured paper. And mounted in a large matte and frame. And hung in a dark corner. In a closet.
08-10-2010, 08:19 PM   #11
Pentaxian
Marc Sabatella's Avatar

Join Date: Sep 2006
Location: Denver, CO
Photos: Gallery
Posts: 10,686
QuoteOriginally posted by jboyde Quote
I'm curious about something. Since high ISO noise increases as the pixel density gets higher, do you think that lowering the image size on the K7 from 14mp to 10 will help lower the noise?
It's something of a myth that noise correlates well with pixel density. It actually correlates much better with *sensor size* and is largely independent of pixel density. People often get the mistaken impression that more pixels means more noise because they make the mistake of viewing the higher resolution image larger, thus magnifying the noise.

QuoteQuote:
Everyone I know that has/had a K200 talked about the smooth noise patterns because of its 10mp sensor.
No, it's 14MP.
08-10-2010, 09:30 PM   #12
Pentaxian
er1kksen's Avatar

Join Date: Oct 2008
Location: Forestville, NY
Photos: Gallery | Albums
Posts: 1,683
Marc, you're certainly correct about the pixel density misconception but the K200D is definitely 10mp. Maybe you thought he meant K20D?

to jboyde: The K7 has superior noise characteristics, regarding the affect noise has on the output rather than pointless 100% views, to the earlier 10mp and 6mp sensors, particularly in print. No image-size adjustments are going to change that. Dedicated NR programs can help reduce the appearance of the noise that does occur, however. Give the NeatImage free trial a try. Lightroom 3 and Topaz Denoise are generally considered the current leaders in noise reduction, though they will cost money.
08-11-2010, 06:43 AM   #13
Senior Member




Join Date: Jan 2010
Location: Oregon
Photos: Gallery | Albums
Posts: 131
Smaller pixels are not necessarily "noiser" than larger pixels. They simply have a smaller bucket (pixel) to catch photons in. For bright lighting conditions, a P&S camera will take nearly the same picture as a larger sensor camera (aside from optics of course), because the number of photons captured in each bucket is much larger than the noise captured in each bucket.

ISO level is just the amplifier setting, before the A/D converter that converts each pixel data from an analog voltage to digital bits. On a K-x, an amplifier setting of 1x (ie no amplification), is the equivalent to ISO 200, and an amplifier setting of 2x is ISO 400. As the amplification is increased, the noise increases proportionally to the image data.

With virtually all camera sensors, reducing the resolution is accomplished by simply subsampling the image pixels - ie throw away some of the pixels to make a smalller image file. Some of the point and shoot cameras have a "digital zoom", where they throw pixels away from the edges to effectively "zoom in". But most SLR's just subsample the pixels across the frame to produce smaller image files. In any case, the amplifier setting is independent of the subsampling, and noise is not affected by using smaller image settings.

With some imaging sensors, specifically the huge CCD arrays they use in telescope facilities, the CCD clocking can be arranged to combine adjacent pixels into larger super pixels. This is called binning. The larger super pixels have a higher dynamic range (ie a bigger bucket to catch photons in), but obviously, have a lower resolution for the whole array.

It would be really neat if camera sensors could do binning, because then as you reduce the image size, you increase the dynamic range of each pixel. But, the camera electronics would have to be significantly different to take advantage of this.
08-11-2010, 07:37 AM   #14
Pentaxian
er1kksen's Avatar

Join Date: Oct 2008
Location: Forestville, NY
Photos: Gallery | Albums
Posts: 1,683
QuoteOriginally posted by leadfoot Quote
It would be really neat if camera sensors could do binning, because then as you reduce the image size, you increase the dynamic range of each pixel. But, the camera electronics would have to be significantly different to take advantage of this.
Well, some of them can... a bit pricier than your average Pentax, though.
08-11-2010, 02:44 PM   #15
Pentaxian
Marc Sabatella's Avatar

Join Date: Sep 2006
Location: Denver, CO
Photos: Gallery
Posts: 10,686
QuoteOriginally posted by er1kksen Quote
Marc, you're certainly correct about the pixel density misconception but the K200D is definitely 10mp. Maybe you thought he meant K20D?
Oops, you're right, I read the final "0" in "K200" as a "D". But for the record, there is no "K200" - there is a K20D, a K200D, and a K2000, but no K200.
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!
camera, change, dslr, image size, iso, loss, noise, photography, sensor, shots, size
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
Image Size vs Document Size vs Resolution vs Resampling vs ... AHHHH! veezchick Digital Processing, Software, and Printing 13 08-02-2010 03:57 PM
Why is ISO lower with the bulb (k-x)? justtakingpics Pentax DSLR Discussion 1 04-22-2010 12:25 PM
GX10 Lower iso1600 noise jamesm007 Pentax DSLR Discussion 1 12-27-2008 12:26 PM
There are some information that K10D with revision 2.1 and higher has lower noise ogl Pentax DSLR Discussion 86 04-25-2008 04:24 PM
Maximum Printed Image Size vs ISO - Successful or Not? Sideways Digital Processing, Software, and Printing 6 08-08-2007 11:00 AM



All times are GMT -7. The time now is 01:10 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