Gary’s Parries 19/02/06

February 19, 2006 | Mark Goldstein | Gary's Parries | 14 Comments |

Gary's ParriesThis week’s Gary’s Parries topics are:

1. Noise Reduction 101
2. New Fuji And Panasonic Digicams (The Good, The Bad, And The Ugly)
3. Kind Words From A Gary’s Parries Fan

Introducing this week’s Gary’s Parries column. Everything you always wanted to know about digital cameras, but were afraid to ask. No question too difficult, or too easy. As a Principal Software Engineer, and a former Assistant Professor of Computer Information Systems, as well as a recording studio owner/operator, and now, a digital camera enthusiast, GARY has more digital camera knowledge in his entire brain than most people have in their little finger. And, in the unlikely event that GARY would not know the answer to your question, he will answer it anyway, true to the spirit of the word “Parries”, a fencing term which, in this context, implies “cleverly evasive answers”. So let your imaginations run wild. Email all of your nagging questions to: garysparries@photographyblog.com, and then, En Garde!

The best question of the week will receive a small prize from the PhotographyBLOG goody bag, so send your questions now. If you would like your name, location, email address, and/or website included in the column with your question, please expressly give your permission in the email, along with the information you would like included. No private information will be included without your consent.

Here are this week’s questions and answers.

QUESTION 1:

How is image noise reduction accomplished in digital cameras?

[Warning: the following is a highly technical discussion. If you are uninterested in such discussions, please skip to Question 2 - Ed.]

ANSWER 1:

The short answer is, not very well.

Digital camera manufacturers are tightlipped about their proprietary methods of image noise reduction, so it is impossible to know what techniques are performed for any specific camera; however, the effects of such noise reduction can be easily compared from camera to camera, as is typically done in camera reviews. If you are unfamiliar with the concept of digital camera image noise, some “excellent” examples can be found in the Image Quality sections of the PhotographyBLOG reviews of the Panasonic Lumix DMC-LX1, Ricoh Caplio GX8, HP Photosmart R817, and Ricoh Caplio R3. For comparison, the reviews of the Fujifilm FinePix F11, Canon PowerShot A620, and Fujifilm FinePix S9500 Zoom demonstrate relatively low noise.

There are a number of different causes of image noise in digital cameras, but they can all be categorized as errors in the voltage representations of an image’s light intensity being measured at each individual photosite. One source of such error is the random fluctuations in the number of photons striking a photosite for a fixed image. Another is the non-uniform capability of each photosite to convert the intensity of light striking it into a proportional electrical charge. Another is the voltage irregularities introduced in the amplification of the electrical charges at the individual photosites. There are other causes of image noise; however, this discussion will be confined to the three sources of error just mentioned.

The easiest of the three sources of error to correct (at least for CCDs, not so much for CMOS Image Sensors) is the effect of voltage irregularities introduced by amplification of the electrical charge measured at each photosite. The reason why correction is easier for CCDs than for CMOS is because there is usually only one such amplifier (or maybe a small number of such amplifiers) used in a CCD system, whereas for CMOS Image Sensors, there are literally millions (one per photosite).

The corresponding correction technique for this source of error is based on obtaining a knowledge of the characteristics of an amplifier’s voltage irregularities, and then applying an appropriate compensation factor to the amplifier’s output voltages. This compensation factor could be determined either at the factory, by obtaining an average value for all cameras of a specific model, or in the field, by using the camera’s firmware to obtain a value specific to that camera. The first method has the advantage of simplicity, while the second method has the advantage of accuracy by compensating for the actual circuitry of the camera, and if performed at the time of each image capture, would even compensate for the prevailing operating conditions. Other schemes offering a blend of simplicity and accuracy are also possible.

The second easiest source of error to correct is the non-uniform capability of each photosite to convert the light striking it into a proportional electrical charge. This too can be determined at the factory so that a compensation factor can be applied; however, in this case, an average value would be useless, since no two CCDs will have the same pattern of photosite non-uniformity. Rather, the factory would need to individually determine a specific non-uniformity pattern for each CCD, and then store those CCD-specific patterns in each corresponding camera.

An easier way to accomplish this would be to have the camera’s firmware determine its own CCD’s non-uniformity pattern. This determination could be made once, and only once, when the camera is first initialized, or better yet, upon each power-up of the camera, or better still, upon each image capture, which would then compensate for any effects on the pattern caused by the operating conditions.

The most difficult source of error to correct is the random fluctuations in the number of photons striking a photosite for a fixed image. Actually, the technique to compensate for this is rather simple, but the effectiveness of the technique can vary depending on the quality of the algorithms used. The first step is to look at the output value of each photosite to determine whether it is in perspective relative to the surrounding photosites for a given image. Then, for each photosite that is not in perspective, an interpolation is performed with the surrounding photosites to adjust the errant photosite’s output value to be more in sync with the surrounding ones.

This technique has the beneficial effect of making an errant photosite less noticeable in the final image by spreading its error over multiple pixels. It could, however, also have a deleterious effect, depending on the level of selectivity used in determining what constitutes an errant photosite. If this determination is made too aggressively, normal photosites which are not quite in perspective with the surrounding photosites, as may occur when there are fine details in an image, could be mistakenly adjusted, thereby eliminating or blurring those fine details. It is the quality of the algorithms used in this determination process, as developed by each camera manufacturer, that is the single most decisive factor for ascertaining whether one camera is noisier than another (all other factors being equal).

With pixel counts skyrocketing and sensor sizes shrinking, increased image noise has become a major problem within the digital camera industry. However, thanks to the many excellent camera reviews and photography blogs available, consumers are now far more educated and in a much better position to demand better from camera manufacturers. In the near future, as CMOS and other technologies evolve, we should expect to see far less noisy image sensors, even with higher pixel counts and smaller sensor sizes. This will be due, in part, to improvements in circuit quality, but more importantly, it will be as a result of improved firmware in combination with additional on-chip circuitry to detect and compensate for the multitude of errors that can occur.

QUESTION 2:

What do you think of the new batch of Panasonic and Fuji cameras introduced this past week? I’m looking for an advanced ultra-compact, preferably with a high zoom, but I’m not sure if they would be any good.

ANSWER 2:

Except for possibly the Fujifilm FinePix F30, I would not buy any of them just yet. Here is why.

The F30 has some great features, the main one being ISOs to 3200. Whether those high ISOs will be usable remains to be seen; however, for now, I am willing to give Fuji the benefit of the doubt based on their solid reputation for low noise. The F30 also has a 2.5” high-resolution LCD, an assortment of manual controls (but no manual focus), some nice scene modes (including an Underwater scene mode with the optional underwater housing), as well as good operational performance and battery capacity. One negative is its lack of OIS, which is not such a big deal for a 3x zoom. However, a much bigger negative (if it is true) is the omission of an AF assist lamp, which would be unforgivable on a camera designed with such otherwise excellent, low-light capabilities.

The other applicable new Fuji is the FinePix F650. This camera sounded almost too good to be true with its 5x zoom and 3.0” LCD in an ultra-compact size. The thing that worries me about the F650 is its 1/2.5” CCD. Every CCD I have seen of that size seems to be plagued by excessive image noise. However, if anyone can avoid the image noise problem, it would be Fuji. Even so, the F650 does not have any OIS, which is not so good for a 5x zoom. It also has no AF assist, which is not good for any camera.

Panasonic did more than a few things right with their new Lumix DMC-FX01. They packed it with 3.6x zoom, 28 mm at the wide end, OIS, 4:3, 3:2, and 16:9 aspect ratios, AF assist, maximum ISO 1600 (in mixed-pixel mode, otherwise maximum ISO 400), 2.5” high-resolution LCD, VGA and wide-aspect VGA video at 30 fps, an abundance of scene modes (including Underwater), and good operational performance and battery life, all in an ultra-compact size. The only thing that bothers me about this camera is, again, its 1/2.5” CCD. If I do not trust Fuji with such a small CCD, I would certainly not trust Panasonic (known for noisy sensors).

The other applicable new Panasonic is the Lumix DMC-TZ1. Its 10x zoom is enough to make one forget that it is not quite an ultra-compact. Add to that its OIS, 4:3, 3:2. and 16:9 aspect ratios, AF assist, maximum ISO 800 (1600 in mixed-pixel mode), 2.5” high-resolution LCD, VGA video at 30 fps, an abundance of scene modes (including Underwater), and good operational performance and battery life, and you have a pretty impressive package. Once again, the only thing that bothers me about this camera is its 1/2.5” CCD. However, one thing puzzles me. This is a 6.37 megapixel CCD, but only 5 megapixels effective. Something is going on here ???

Before making any purchasing decisions on these cameras, I would wait until after PhotographyBLOG and others have reviewed them thoroughly. If it turns out that the new 1/2.5” CCDs have licked the noise problem that plagued last years models, these cameras will be awesome.

Considering Panasonic’s expertise in building cameras with excellent feature sets, but falling short in the noise performance of their image sensors, and considering Fuji’s expertise in building cameras with excellent noise performance by using its proprietary CCD technology, but neglecting to include important features such as OIS and AF assist, wouldn’t it be nice if the two companies got together to collaborate on producing a camera with the best of both worlds?

QUESTION 3:

Gary, you’re an idiot !!! You spend all this time searching for a camera for your wife (if she even exists), and then you end up buying her a printer. Now you claim to still be looking for a camera, hoping something better will be announced at PMA. If there is, you’ll still find something wrong with it. Meanwhile, you make your wife use an antiquated Canon G3. If you had any brains, you would have bought her a Ricoh R3 or a Samsung L55W, or even a Panasonic LX1. You say it was because you already had two strikes against you and did not want to strike out, but IMHO, your decision was strike three, so you are out. I’m surprised your wife did not leave you. Not because you got three strikes, but because you got no balls.

ANSWER 3:

Thank you for those kind words. BTW, do you like to hunt?


Column photo “The Photographer” by Brenda LaFleur of Brenda LaFleur Photography.



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#1 Gary's Parries

Addendum to Answer #2 -- Judging from Mark's newly added sample
photos from Lisbon, Portugal using a preproduction Panasonic Lumix
DMC-FX01 and DMC-TZ1, I would have to say that Panasonic's new
6.37 total megapixel 1/2.5" CCD is greatly improved over last year's
crop of 5 megapixel 1/2.5" CCDs.

http://tinyurl.com/mhjcq
http://tinyurl.com/nwmkv

9:48 pm - Sunday, February 19, 2006

#2 Nick

"GARY has more digital camera knowledge in his entire brain than most people have in their little finger"

Should this be the other way around? Or do we all, indeed have more knowledge than Gary?

; )

8:39 am - Monday, February 20, 2006

#3 nick in japan

Comment #2 was submitted by someone other than "nick in japan" Indeed a new-comer, not accustomed to "Pogoisms" ( humor caused by a genetic mutations originally initiated by continual bouncing) note: there is no cure, it is not harmful, but, is contagious!

9:06 am - Monday, February 20, 2006

#4 GARY POGODA

If I'm not mistaken, the Nick in comment #2 is none other than "the
people photographer", whose PhotographyBLOG portfolio I critiqued,
and he is just returning the "favor". I think you (nick in japan) would
appreciate my comment #2 at that thread:

http://tinyurl.com/oef65

BTW, Nick ("the people photographer"), how did your "delivery room
shoot" go?

11:10 am - Monday, February 20, 2006

#5 nick in japan

Could be! I went to his site, looks like he stays real busy! Wonderful stuff!!

11:30 am - Monday, February 20, 2006

#6 GARY POGODA

So, I'm dying to know. What did you think of Mark's Panasonic FX01
photos? IYO, do they look clean, or am I just jumping the gun?

This camera has close to your ideal feature set: 28mm wide end, OIS,
16:9 aspect ratio (but only at 4.5 megapixels), and true ultra-compact
dimensions.

12:19 pm - Monday, February 20, 2006

#7 Gary's Parries

Update: According to its spec sheet at Fuji's website, the F30 DOES
have AF assist. It also has image stabilization. The F650 has neither.
Thanks for the link, Paul.

http://tinyurl.com/maujf

Update: It was pointed out to me by several people (Prog, Zoltan, and
Josh) that my evaluation of Mark's photos for the Panasonic FX01 and
TZ1 might have been a bit premature since those images were resized
to 800 x 600, which would mask the noise. My point that a noisy image
would still show signs of noise even at 800 x 600 was supported by the
Ricoh R3 image supplied by Prog, but Josh's point prevailed, namely, if
the same heavy-handed noise reduction used on the FX9 (where image
details are sacrificed to mask the noise) were also used on the FX01, it
might be difficult to detect at 800 x 600.

Update: According to a link supplied by Olivier_G, the Panasonic TZ1's
CCD might be 5.3 megapixels, not 6.3 as indicated in the press release,
which would make more sense considering it is 5.0 megapixels effective.

http://index.hu/tech/digicam/mutat_mc?formid=954

12:22 pm - Tuesday, February 21, 2006

#8 nick in japan

The FX01 photos are very nice! As are most pictures from just about everything on the market, are they a breakthrough, enough to go gaa-gaa over? No! Call me stupid but I have the breakthrough cameras I want right now, in the LX-1! Not a pro compact, but built like one. To be honest, the best deal I can get right now on the Kodak 570 is $337 here in Japan, no tax, and the 23mm alone is worth that. I went gaa-gaa over the stiching program too. I get this feeling that someone is gonna make the breakthrough camera soon with a quality sensor that will rival the 10D.
On that subject, weren't the portfolios of Nick Stubbs more proof that folks dont really need anything more than a 10D?

1:26 pm - Tuesday, February 21, 2006

#9 GARY POGODA

I think we're all waiting for that breakthrough pocket camera, but not
this year. Is it my imagination, or are camera companies introducing
more cameras to their lineup in one fell swoop than ever before? It's
becoming almost impossible to keep up with the flow. But I am really
glad that I held off buying a camera for my wife until after PMA.

I was impressed with the specs from Vivitar's 10 megapixel, 6x zoom
ultra-compact, the ViviCam X60. The same with Canon's 6 megapixel,
4x zoom ultra-compact with IS, the PowerShot SD700 IS. Also Nikon's
8.1 megapixel, 3.5x zoom ultra-compact with Vibration Reduction, the
Coolpix P3 with WiFi, or the P4 without. Plus, the previously mentioned
Fujis and Panasonics. It's all a bit overwhelming.

7:52 pm - Tuesday, February 21, 2006

#10 Gary's Parries

Update: It has been pointed out to me that the Fuji F30's IS, which is
called Picture Stabilization (PS) by Fuji, is not true OIS; rather, it uses
the high sensitivities of the F30 to automatically set the optimum ISO
and shutter speed for preventing blur due to both camera shake and
subject movement, unlike OIS which can compensate only for camera
shake. While the combination of OIS and PS would have been ideal, if
the F30's ISO 1600 and ISO 3200 are actually usable, the lack of OIS
might not be such a big deal. Good eye, Paul.

BTW, that also explains why Fuji did not include PS with their 5x zoom
F650 (where it would have been even more useful) since its maximum
ISO is only 400, and not high enough for an effective PS.

9:04 pm - Tuesday, February 21, 2006

#11 Nick Stubbs

Hello Chaps,

I only pointed out the "flaw"? (intentional or otherwise) in that sentence (comment 2) because after reading Gary´s incredible take on noise reduction, my brain went into meltdown and I felt very inadequate...nice piece Gary!

I agree with a couple of other points such as the megapixel race and how unecessary it really is. I came across an article (could have been here, don´t remember now)?!? that suggests a move away from chasing pixels and more towards HDR (high Dynamic Range).

Here is a link:

http://www.cybergrain.com/tech/hdr/

All very interesting stuff and similar to us all having to buy (if we so desire) new TV´s that are High Definition (HD) ready. Will a new breed of cameras soon to be announced be "HDR ready"?

Lastly, I agree 100% about manufacturers throwing out camera after camera for whatever reason....my RSS feed pings continuously all day long with Canon announce this and Sony release that! Where will it all end?

I gave up looking for a decent point and shoot back-up a while ago when my research drove me mad. I now just use the 20D as back-up.

BTW, the "delivery room shoot" was a resounding success and our daughter was born happy and healthy (nearly 5 months old now)!

Cheers,

Nick

10:02 pm - Friday, February 24, 2006

#12 nick in japan

Congrats! My last two children also posed for me during their entrance into this world, I made a mistake tho and used color film, ended up changing them to Black and white, and sepia!
Photoshop CS2 has exactly what you need for High Dynamic Range utilization, it's called "Shadow/Highlight" ( Image>Adjustments>Shadow/Highlight) I use it quite often especially with "Match Color"
This is probably my most used feature in the PS upgrade, accomplishes the dynamic range increase very well. Layering of your working duplicates can accomplish similar results also, lottsa ways to get there, with you being in control, all the way!
Back to the delivery room, the best shots of both my shoots were the moment that the doctor showed Miho, and Joe to my wife, the first time she saw them is the moment that was the best.
I love your comment, Nick, " I now just use the 20D as back-up"!!!

11:47 pm - Friday, February 24, 2006

#13 Nick Stubbs

Thanks Nick (in Japan). I was there for both deliveries too, my respect for women increased dramatically after those times (except when she kept getting in the way of a decent shot...HUH! WOMEN! ;)

The 20D comment was a little sarcastic, did you guess? I have actually used the 1d mkii for about a year now but still prefer the images from the 20D, especially portraits and indoor shots. What a camera and the 30D is by no means enough of an upgrade to make me want to switch. They raised the bar quite high with that camera.

I would still like a nice P and S as back up....if only they could release something like this...

http://dc.watch.impress.co.jp/static/present/eos1_14l.jpg

Hoho!

Nick

7:01 am - Saturday, February 25, 2006

#14 nick in japan

Perfect, kinda like those little minox replicas. I have found that the p/s cameras I am usung now, the Pentax S6 and LX-1s do a nice job with portraits and close-ups with a focal length out to about 86mm, the noise curse rears it's ugly head in those skys and large detail-less areas. Nothing like a little, unabtrusive pocket camera to get those candid facial shots.
About the backup, thought you may have referred to the 20 being a backup for the 10!
Love your work!

8:10 am - Saturday, February 25, 2006