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Phil's Noise Tests for Sigma: Accurate??

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tom jacobson

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Phil notes in his review of the Sigma that as the ISO goes up, the contrast and sharpness goes down. I think there is a reason for this. It is an attempt by Sigma to hide the true noise levels. If you adjust the contrast and sharpness of the higher ISO shots on the Sigma to match the D60 or whatever, I think you will see a much different picture of noise levels. Using the "normal" settings of the camera has played into the hands of the self serving Sigma/Foveon folks. Guys, they are hiding the noise!!

PS Do you remember the first press releases for the Foveon chip, where they showed side by side comparisons? Remember the side by side for color accuracy? I adjusted the two for color saturation and then they were identical! They were playing one of their tricks. Where is this fantastic color accuracy now? Haven't seen a single example of the Sigma outdoing any camera in color accuracy.--
TJ
 
Absolutely, they probably do have noise reduction, I wouldn't call it "hiding", a lot of manufacturers do noise reduction to one degree or another.

Unless the camera allows me to turn it off I can do nothing but measure noise in the final image.
tom jacobson said:
Phil notes in his review of the Sigma that as the ISO goes up, the
contrast and sharpness goes down. I think there is a reason for
this. It is an attempt by Sigma to hide the true noise levels. If
you adjust the contrast and sharpness of the higher ISO shots on
the Sigma to match the D60 or whatever, I think you will see a much
different picture of noise levels. Using the "normal" settings of
the camera has played into the hands of the self serving
Sigma/Foveon folks. Guys, they are hiding the noise!!

PS Do you remember the first press releases for the Foveon chip,
where they showed side by side comparisons? Remember the side by
side for color accuracy? I adjusted the two for color saturation
and then they were identical! They were playing one of their
tricks. Where is this fantastic color accuracy now? Haven't seen
a single example of the Sigma outdoing any camera in color
accuracy.--
TJ
Click to expand...
--
Phil Askey
Editor / Owner, dpreview.com
 
Phil Askey said:
Absolutely, they probably do have noise reduction, I wouldn't call
it "hiding", a lot of manufacturers do noise reduction to one
degree or another.
Click to expand...
Yes, other manufacturers do noise reduction, but not image reduction!
Member said:
Unless the camera allows me to turn it off I can do nothing but
measure noise in the final image.
Click to expand...
Well, you could take two images that have equal contrast and sharpness at the same ISO settings and compare those. I feel you should adjust up the contrast and sharpness before comparing the images of the Sigma to other cameras. I am sure that someone on this site will come up with some more accurate comparisons. Phil, don't get me wrong, I love you (and your wife!). You do great work. BUT, in this case Sigma has rigged the output to make your tests show their camera in a good light. They are not stupid (far from it) and know how many people look at your reviews before purchasing. Their "noise reduction" is shameless!! If you reduce the overall contrast and sharpness of in image, the noise magically goes way down. However, when you then adjust the image to look good, watch out!

--
TJ
 
I don't quite follow your logic. Are you saying that they should not try to produce the best possible image? Or do you mean that they should include the "noise" and then let you have the option of getting rid of it?

Every camera manufacturer out there is trying to produce the best possible image with their technology, not the worst or middling. Do you think that the Bayer cameras should get rid of their AA filters so that we can see what a mess is there? I don't. I am very happy that Sony takes the time to clean up the image before giving it to me to fiddle with.

I would not call this hiding but sensible. It certainly isn't shameless.
tom jacobson said:
Phil Askey said:
Absolutely, they probably do have noise reduction, I wouldn't call
it "hiding", a lot of manufacturers do noise reduction to one
degree or another.
Click to expand...
Yes, other manufacturers do noise reduction, but not image reduction!
tom jacobson said:
Unless the camera allows me to turn it off I can do nothing but
measure noise in the final image.
Click to expand...
Well, you could take two images that have equal contrast and
sharpness at the same ISO settings and compare those. I feel you
should adjust up the contrast and sharpness before comparing the
images of the Sigma to other cameras. I am sure that someone on
this site will come up with some more accurate comparisons. Phil,
don't get me wrong, I love you (and your wife!). You do great
work. BUT, in this case Sigma has rigged the output to make your
tests show their camera in a good light. They are not stupid (far
from it) and know how many people look at your reviews before
purchasing. Their "noise reduction" is shameless!! If you reduce
the overall contrast and sharpness of in image, the noise magically
goes way down. However, when you then adjust the image to look
good, watch out!

--
TJ
Click to expand...
 
Laurence,

I think what Tom was saying is that you can do noise reduction without taking the simplistic approach of reducing the contrast and sharpness. Using your example, Sony has cleaned up their image without significantly degrading the image quality. They did this by not simply reducing contrast but by using a more sophisticated approach. You can then make adjustments to your photo without getting all that noise back.

(One should realize that even the best noise reduction algorithms or PS actions will result in some loss of quality. That's why it's critical to reduce the amount of noise the sensor generates in the first place.)

If, AND THIS IS A BIG IF, Sigma has taken the approach of reducing contrast and sharpness as a way of reducing apparent noise in high ISO images, you'll gain a lot of that noise back when you to to make adjustments. If that is the case, they really haven't reduced the noise, just hidden it.

Because you have to post-process the RAW images, it's possible that Sigma could change their approach to noise reduction in a later version of Photo Pro and not affect the contrast or sharpness of the photo.

Kevin
Laurence Matson said:
I don't quite follow your logic. Are you saying that they should
not try to produce the best possible image? Or do you mean that
they should include the "noise" and then let you have the option of
getting rid of it?

Every camera manufacturer out there is trying to produce the best
possible image with their technology, not the worst or middling. Do
you think that the Bayer cameras should get rid of their AA filters
so that we can see what a mess is there? I don't. I am very happy
that Sony takes the time to clean up the image before giving it to
me to fiddle with.

I would not call this hiding but sensible. It certainly isn't
shameless.
Click to expand...
 
tom jacobson said:
Yes, other manufacturers do noise reduction, but not image reduction!
Click to expand...
tom jacobson said:
BUT, in this case Sigma has rigged the output to make your
tests show their camera in a good light.
Click to expand...
How is this different then say Sony having too much sharpness in their photos that you cannot turn off? Each camera mfg'ers do built-in adjustments according to their own standards, weither you want it or not.

Lets please not make it sound like Sigma is doing illegal stuff here.

--
jc
Sony F707
http://www.reefkeepers.org/gallery/f707
http://www.reeftec.com/gallery
 
Jimmy,

I wouldn't call it illegal because it's not. However, it's not the best way to reduce noise in a photo. IF this is the approach Sigma has taken to reduce noise in high ISO photos, then I look at this the same way I look at their problems with JPEG compression - an error on their part that should be able to be corrected in a later version of the software.

Kevin
Jimmy Chen said:
Jimmy Chen said:
Yes, other manufacturers do noise reduction, but not image reduction!
Click to expand...
Jimmy Chen said:
BUT, in this case Sigma has rigged the output to make your
tests show their camera in a good light.
Click to expand...
How is this different then say Sony having too much sharpness in
their photos that you cannot turn off? Each camera mfg'ers do
built-in adjustments according to their own standards, weither you
want it or not.

Lets please not make it sound like Sigma is doing illegal stuff here.

--
jc
Sony F707
http://www.reefkeepers.org/gallery/f707
http://www.reeftec.com/gallery
Click to expand...
 
Kevin and Tom,

Perhaps I am a bit touchy after all the (other) noise in the run-up to this camera. In any case, proceeding on the assumption that the software will permit a breadth of changes, I would imagine that there is a great deal one can do to control this issue. Furthermore, a software upgrade is easy enough if better alogrithms are found down the road.

I have said all along that this camera will appear to require very accurate metering, which I don't think a bad thing. I also feel that the tendency will be to underexpose and push rather than overexpose and recover. That assumption comes from the so-called blowouts.

For me, the noise issue falls in the same category. This is a narrow-range camera, which is not a deal killer as far as I am concerned. It is like using Kodachrome 25, which was great but limited. With the SD9, I will learn to use a real flash again, dust off my metering skills, and start to think again. Furthermore, the RAW format will slow down the old snap-image reflex, which I should never have allowed to get started in the first place.

Laurence
Kevin Blair said:
I think what Tom was saying is that you can do noise reduction
without taking the simplistic approach of reducing the contrast and
sharpness. Using your example, Sony has cleaned up their image
without significantly degrading the image quality. They did this by
not simply reducing contrast but by using a more sophisticated
approach. You can then make adjustments to your photo without
getting all that noise back.

(One should realize that even the best noise reduction algorithms
or PS actions will result in some loss of quality. That's why it's
critical to reduce the amount of noise the sensor generates in the
first place.)

If, AND THIS IS A BIG IF, Sigma has taken the approach of reducing
contrast and sharpness as a way of reducing apparent noise in high
ISO images, you'll gain a lot of that noise back when you to to
make adjustments. If that is the case, they really haven't reduced
the noise, just hidden it.

Because you have to post-process the RAW images, it's possible that
Sigma could change their approach to noise reduction in a later
version of Photo Pro and not affect the contrast or sharpness of
the photo.

Kevin
Laurence Matson said:
I don't quite follow your logic. Are you saying that they should
not try to produce the best possible image? Or do you mean that
they should include the "noise" and then let you have the option of
getting rid of it?

Every camera manufacturer out there is trying to produce the best
possible image with their technology, not the worst or middling. Do
you think that the Bayer cameras should get rid of their AA filters
so that we can see what a mess is there? I don't. I am very happy
that Sony takes the time to clean up the image before giving it to
me to fiddle with.

I would not call this hiding but sensible. It certainly isn't
shameless.
Click to expand...
Click to expand...
 
Laurence,

That is one of the advantages of making one shoot in RAW and post-process the images in Photo Pro. Although you can't change the underlying sensor performance, you can more easily make changes in how those images are handled (noise, JPEG compression, etc.).

Speaking of metering issues, one of the forward-thinking things that I think Sigma incorporated into the camera was the separate RGB histograms. Since it appears that very intense reds can cause blowouts, the separate histograms should allow you to identify potential trouble spots in a scene and adjust you exposure accordingly.

Kevin
Laurence Matson said:
Kevin and Tom,

Perhaps I am a bit touchy after all the (other) noise in the run-up
to this camera. In any case, proceeding on the assumption that the
software will permit a breadth of changes, I would imagine that
there is a great deal one can do to control this issue.
Furthermore, a software upgrade is easy enough if better alogrithms
are found down the road.

I have said all along that this camera will appear to require very
accurate metering, which I don't think a bad thing. I also feel
that the tendency will be to underexpose and push rather than
overexpose and recover. That assumption comes from the so-called
blowouts.

For me, the noise issue falls in the same category. This is a
narrow-range camera, which is not a deal killer as far as I am
concerned. It is like using Kodachrome 25, which was great but
limited. With the SD9, I will learn to use a real flash again, dust
off my metering skills, and start to think again. Furthermore, the
RAW format will slow down the old snap-image reflex, which I should
never have allowed to get started in the first place.

Laurence
Click to expand...
 
The differences Phil noted were very small and only apparent after examing lots of images closely.
tom jacobson said:
Phil Askey said:
Absolutely, they probably do have noise reduction, I wouldn't call
it "hiding", a lot of manufacturers do noise reduction to one
degree or another.
Click to expand...
Yes, other manufacturers do noise reduction, but not image reduction!
tom jacobson said:
Unless the camera allows me to turn it off I can do nothing but
measure noise in the final image.
Click to expand...
Well, you could take two images that have equal contrast and
sharpness at the same ISO settings and compare those. I feel you
should adjust up the contrast and sharpness before comparing the
images of the Sigma to other cameras. I am sure that someone on
this site will come up with some more accurate comparisons. Phil,
don't get me wrong, I love you (and your wife!). You do great
work. BUT, in this case Sigma has rigged the output to make your
tests show their camera in a good light. They are not stupid (far
from it) and know how many people look at your reviews before
purchasing. Their "noise reduction" is shameless!! If you reduce
the overall contrast and sharpness of in image, the noise magically
goes way down. However, when you then adjust the image to look
good, watch out!

--
TJ
Click to expand...
 
Iwill confess that I have never caught on to the histogram action. Nothing against anyone who has other that a bit of jealousy on my part. I still believe that the best metering tool made is a hand-held 1° spot meter. Nothing has ever worked better for me. It is still all I use for film. I cannot imagine how it would be otherwise with the SD9. I will also confess that the point and shoot quality of the Sony's I have used has made me a bit lazy with digital.

Having said that, I assume that I will have to go through a series of tests just as before with a new film. Afterwards, it is very similar to developing film in the work process.

I have always believed that it is better to slow things down with photography and not speed them up. Time for thinking is important for me at each step. Those who do not have that luxury have other methods, of course.
Kevin Blair said:
That is one of the advantages of making one shoot in RAW and
post-process the images in Photo Pro. Although you can't change the
underlying sensor performance, you can more easily make changes in
how those images are handled (noise, JPEG compression, etc.).

Speaking of metering issues, one of the forward-thinking things
that I think Sigma incorporated into the camera was the separate
RGB histograms. Since it appears that very intense reds can cause
blowouts, the separate histograms should allow you to identify
potential trouble spots in a scene and adjust you exposure
accordingly.

Kevin
Laurence Matson said:
Kevin and Tom,

Perhaps I am a bit touchy after all the (other) noise in the run-up
to this camera. In any case, proceeding on the assumption that the
software will permit a breadth of changes, I would imagine that
there is a great deal one can do to control this issue.
Furthermore, a software upgrade is easy enough if better alogrithms
are found down the road.

I have said all along that this camera will appear to require very
accurate metering, which I don't think a bad thing. I also feel
that the tendency will be to underexpose and push rather than
overexpose and recover. That assumption comes from the so-called
blowouts.

For me, the noise issue falls in the same category. This is a
narrow-range camera, which is not a deal killer as far as I am
concerned. It is like using Kodachrome 25, which was great but
limited. With the SD9, I will learn to use a real flash again, dust
off my metering skills, and start to think again. Furthermore, the
RAW format will slow down the old snap-image reflex, which I should
never have allowed to get started in the first place.

Laurence
Click to expand...
Click to expand...
 
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