From: none on
On Thu, 17 Jul 2008 22:15:06 GMT, John Sheehy <JPS(a)no.komm> wrote:


>
>That makes no sense at all. I am not comparing cameras; I am comparing
>the effects of pixel density. I am fighting the myth that pixel noise
>determines image noise, and that Pixel DR determines image DR, and
>pointing out that with similar era-technology, the effecticve *image*
>read noise can be significantly lower with higher pixel density, because
>read noise does not increase at a rate equal to the reciprocal of pixel
>pitch, when you miniaturize pixels.
>

That may be what you *think* you're comparing, but you can't negate
the effects of the camera - i.e., you're really comparing whole
systems, not just sensors. You have no way to introduce a "control"
so that you can eliminate the effects of the rest of the "system".

Pixel densities of the sensors is not the only variable in the
comparison that you are changing, and so you can't account for those
other variables in such a way to allow only a pixel density
comparison.

As a real, scientific study, this effort fails horribly, to show what
you were setting out to demonstrate.

Designing of valid experiments is not something easily done. Unless
you're really skilled in that, you should accept that your efforts may
be in vain.
From: John Sheehy on
ASAAR <caught(a)22.com> wrote in
news:6rov74hjr208gua15e3bcv8c7hm4sq62c7(a)4ax.com:

> On Thu, 17 Jul 2008 22:15:06 GMT, John Sheehy wrote:

>> That makes no sense at all. I am not comparing cameras;

> Only because sense can't penetrate your thick skull. People don't
> buy sensors.

I don't care what people do. I care about what gives or potentially
gives the best imaging.

> They buy and use cameras. If you can't show that your
> warped theory provides any real world benefit, you may want to
> examine why that is so.

Why in the world would anyone with any amount of intelligence, with the
history of all that came before us, believe that the best things already
exist?

> BTW, what you failed to understand is that
> the direct comparison would be between the images, not the cameras.
> See above . . .

The direct comparison of what? I am getting the sense that most of the
critics here have no viable working model in their heads of what a sensor
is, and what it does, yet they feel obliged to make all kinds of comments
assuming some kind of magic.

>>> What Sheehy has done instead is to compare portions of each sensor
>>> having the same actual area.
>>
>> That is the only way to compare pixel density, which is the only
>> thing I wish to demonstrate here.
>
> I hate to break it to you, but you're demonstrating much more than
> you realize.

I know; I clearly don't have patience for stupid people; that is obvious.

>> I don't start threads to state the obvious.

> They are obvious because the threads are all rehashes of what
> you've previously posted. Unconvincing before, unconvincing now.

And where is your counter-evidence? There is none. There is no evidence
that higher pixel density lowers DR or increases noise. Every shred of
so-called evidence assumes a 100% pixel view, uses JPEGs, or unequal
conversions (No commercial RAW converter converts different cameras the
same way; Brands that have a history of high RAW noise get extra NR by
default, just like the manufacturer's JPEGs do).

>> The big myth going around today is that "cramming" more pixels
>> into a given sensor size deteriorates image quality, and that is
>> generally nonsense.

> Your nonsense continues. Consider DPReview's conclusions about
> your pet FZ50. They admitted that it had "excellent resolution",
> and "under the right conditions it produces superb output." It
> seems that the myth creator is *you*.

What myth? I think the FZ50's JPEGs are miserable - that's the camera's
big downfall. It should have had two options; honest, simplehonest
conversions for those who know how to deal with small-sensor noise on
their own, and Fuji-like over-the top noise reduction. I don't know why
they make the choice that they do here; maybe something as simple as
someone well-liked by the CEO (his nephew) coming up with the NR that is
pleasing to no one.

> DPReview recognizes what you
> apparently can't, that cramming too many pixels into the sensor
> increases that probability that more inferior images will be
> produced because conditions aren't always optimal.

Guess you're out of the loop, but there's a big showdown going on at
DPReview right now, because the intelligesia there have challenged Phil
on his pixel-centric, noise-reduced, unequal conversion comparisons, and
it has become clear to him that his most knowledgeable forum members
almost unanimously believe that the conclusions are invalid. He was
engaged in such a discussion, and when asked for proof of his viewpoint,
he became mute. Hopefully, he's doing a lot of thinking about this.

Of course, for cameras that don't do RAW, he can't possibly compare equal
conversions, but for those, he still doesn't have to compare at the pixel
level. And guess what, his most recent comparison, written since his
silence, has had one image scaled to meet the other.

> If everything you say about pixels evaluated for noise and DR at
> low ISOs is true, it still doesn't matter if you can't show how that
> will help people to select a camera that produces superior images.

Who said I was trying to tell people what camera to buy? Boy, do you
have a warped sense of reading. No matter how many times I tell you I
think the JPEG output of the FZ50 is not the best, and no matter how many
times I tell you I am only using it's pixels because of their RAW
qualities, you will keep on insisting in your warped mind that I am a
rabid fanboy, justifying his purchase.

> This conclusion is far clearer and far more helpful for that purpose
> than anything you've ever written.

Many things that people find clear are actually false, under the hood.
People like simplicity, more than they are interested in truth.

>> Producing a camera this size with 35-420mm (equiv.) F2.8-3.7
>> zoom lens means you have to use a small sensor, and small
>> sensors mean compromise because noise is always going to be
>> an issue.

True so far, except that at base ISO the RAW images are quite acceptable;
as good as a Canon DSLR at ISO 400 or 500.

>> I completely understand why Panasonic chose to jump
>> from 5 to 8 to 10 megapixels in three generations of its flagship
>> FZ camera - it's a lot easier to sell a camera on pixels than
>> picture quality, and the average consumer (and it must be said
>> the average camera store buyer) uses megapixels above all else
>> when sorting cameras into categories. Panasonic's marketeers
>> knew full well that with 10MP 'consumer' SLRs on the horizon
>> (and 10MP the new high end for compacts too) the FZ50 needed
>> a headline 'resolution' that kept it near the top. I do, however,
>> think it was a mistake to think that the FZ50 buyer is the 'average'
>> consumer, unable to base decisions on anything but megapixels...

There are three layers to this onion. There is the hypothetical blind
consumer who thinks that more MPs are always better in every way. Then
below that there are people who think that more MPsruins images in a
given sensor size. Below that are the people who understand that there
really is some value in higher pixel density, an that most of the
perceived problems by the middle layer are due to NR and display
technology problems (100 PPI monitors are a cruel joke!; so is
Photoshop's noisy zoom at less than 100%), and that the underlying data
is almost always better at higher pixel densities, except when the MFR
starts taking shortcuts, such as the cheaper late stage/ADC circuits to
save money (ala Canon 450D and Pentax K20D, whose high-ISO noise improved
over their predecessors', while the low ISO noise increased)

>> And so what we have is a camera that stretches its sensor to
>> almost breaking point and compensates for the lack of sensitivity
>> in anything but the brightest conditions by using excessive noise
>> reduction. The FZ50 is an excellent 5 or 6MP camera, but a
>> rather less impressive 10MP camera. Is this a problem? Probably
>> not - by the time the huge files have been shrunk down for
>> printing or viewing on-screen they look fantastic,

Maybe that should have been a hint to himself and to you. All sensors
should be compared at the same size output; not zoomed in 100% to the
pixels. We take images, not pixages.

>> and the
>> handling and features are quite simply peerless. But do not, for
>> a minute, think that the 10 million pixels you're getting with the
>> FZ50 bear anything but a passing resemblance to the 10 million
>> pixel images you'll get from a good SLR once you get above
>> ISO 100, or once light levels start to drop.

I agree with that comment 100%. Are you surprised? If you are, perhaps
you have some major problems when reading my words. I have NEVER, EVER
claimed that a 1/1.8" sensor can outperform an APS-C sensor, except
perhaps at read noise; quite a few compacts have the same or less read
noise than some DSLRs. If you think I just contradicted myself; think
again. Read noise is not the only noise. Lower shot noise is had in the
bigger sensors (given equal exposure, the image shot noise is inversely
proportional to the square root of the sensor area, times the quantum
efficiency).

>> And so, to sum up; for the serious user the FZ50 is without doubt
>> the best equipped, best specified and best handling 'bridge camera'
>> on the market today, and under the right conditions it produces
>> superb output. It is a rewarding and enjoyable photographic tool
>> that - once you've learned its quirks - offers a compact 'all-in-one'
>> solution to anyone wanting a huge zoom range without all that lens
>> changing and all that bulk. Inevitably this involves a certain amount
>> of compromise; the smearing of fine, low contrast detail that is the
>> hallmark of the Venus III engine limits the FZ50 to low ISO settings
>> for any serious photography unless you're happy to accept that
>> you'll never be able to produce big enlargements. For me this is an
>> acceptable compromise, and - though I wish Panasonic would drop
>> the megapixel race and concentrate on picture quality - it does
>> produce excellent printed results.

That's because the nose isn't in the monitor at 100% zoom. You do
realize that 100% zoom on a monitor means a printed image 3 to 4 feet
wide, something you're not even likely to try, don't you?

Yet, people make judgements condemning tiny-sensor cameras for noise at
100% pixel view.

>> If this had been a mould-breaking
>> 5 or 6 megapixel with excellent low noise performance throughout
>> the ISO range (and particularly up to ISO 800) it would no doubt
>> have performed considerably better and would have been an easy
>> choice for a Highly Recommended. As it is it just squeezes in thanks
>> to its many other outstanding qualities - and only for those users
>> who can live without anything over ISO 200.

What Phil does not understand is that the FZ50 has less RAW noise than
just about any 5 or 6 MP camera when downsampled to 5 or 6 MP, or any 5
or 6 MP camera upsampled to meet the 10.1MP at full resolution, based on
the RAW data. The problem with NR is that the manufacturers are
approaching it from a pixel-centric viewpoint, and as the per-pixel shot
noise rises as they increase the pixel density, they lose the ability to
easily assess what pixels need to be squashed, as individual pixel noise
starts to approach hot pixel levels, so, instead of that waxy, continuous
texture at 5MP, they have little pock-marks in the waxy texture at 10.1
MP, from the pixels that broke the threshold. If there were no NR at
all, except a small amount of high-frequency chroma filtering, this would
not even be an issue when viewing 5 and 10 MP images at the same size;
the higher individual pixel noise would dissolve more into the scene,
with potentially lower image-level read (but not shot) noise. The shot
noise would only improve if the QE improved. There is little room for QE
improvement in the FZ50's sensor; according to some sensor experts on
DPReview forums (industry insiders), the FZ50 microlens/nMOS sensor
design is top-notch.

--

<>>< ><<> ><<> <>>< ><<> <>>< <>>< ><<>
John P Sheehy <JPS(a)no.komm>
><<> <>>< <>>< ><<> <>>< ><<> ><<> <>><
From: John Sheehy on
Steve <steve(a)example.com> wrote in
news:r14084pd0bfcgb14qej7eiquttaua3f4tn(a)4ax.com:

> On Thu, 17 Jul 2008 22:15:06 GMT, John Sheehy <JPS(a)no.komm> wrote:

>>That makes no sense at all. I am not comparing cameras; I am comparing
>>the effects of pixel density. I am fighting the myth that pixel noise

> Actually, you're not doing that at all. What you are doing is
> comparing the effects of resolution at the focal plane. No one can
> argue that higher pixel density gives higher resolution at the focal
> plane. And that's the only thing your test proves ... the obvious.
> Only you can argue that this somehow translates to higher pixel
> density gives better noise and DR performance in any real world image.
> It doesn't, and the rest of the world knows that to be true no matter
> how much you profess otherwise.

I don't know what to say to you; you are being totally illogical. Can
you find *any* way in which the 400D crop is less noisy than the FZ50
one?

I don't know what it is, but I can not for the life of me figure out how
people can hold such unrealistic models in their heads. Then again, I'm
the guy who got 100% on all his math and most of his science tests,
without studying, so maybe I'm expecting too much.

My FZ50 crop shows what the resolution and noise would look like with the
same exposure, same scene, etc, etc, with FZ50 pixels filling the same
area of the 400D sensor that its bigger pixels now fill. How do the
small FZ50 pixels not have less noise?

--

<>>< ><<> ><<> <>>< ><<> <>>< <>>< ><<>
John P Sheehy <JPS(a)no.komm>
><<> <>>< <>>< ><<> <>>< ><<> ><<> <>><
From: John Sheehy on
none <nobodyhome(a)yahoo.com> wrote in
news:v16184pv7itqffgdal482kjcoj65nu71hm(a)4ax.com:

> On Thu, 17 Jul 2008 22:15:06 GMT, John Sheehy <JPS(a)no.komm> wrote:
>>That makes no sense at all. I am not comparing cameras; I am comparing
>>the effects of pixel density. I am fighting the myth that pixel noise
>>determines image noise, and that Pixel DR determines image DR, and
>>pointing out that with similar era-technology, the effecticve *image*
>>read noise can be significantly lower with higher pixel density,
>>because
>>read noise does not increase at a rate equal to the reciprocal of pixel
>>pitch, when you miniaturize pixels.
>>
>
> That may be what you *think* you're comparing, but you can't negate
> the effects of the camera - i.e., you're really comparing whole
> systems, not just sensors. You have no way to introduce a "control"
> so that you can eliminate the effects of the rest of the "system".

Nonsense. An APS camera could be designed with the equivalent of several
FZ50 sensors read in parallel, with the same noise. Hell, if your camera
is not meant to be sold at $450, you could use even better
readout/digitization electronics if you wanted to. The only relevant
"system" issue is the amount of read noise added by the camera. Shot
noise per pixel and dark current noise has *NOTHING* to do with the
system.

> Pixel densities of the sensors is not the only variable in the
> comparison that you are changing, and so you can't account for those
> other variables in such a way to allow only a pixel density
> comparison.

Nonsense. The only valid difference is the optics, but if you think
about it, there is no way the optics could ever match the FZ50 in the
400D version, because even if you used the sharpest lens available, the
maximum pixel-to pixel contrast imposed by the AA filter would still be
there, and this would be stretched when the image ws scaled 289%; there
is no way for the 400D to win, it loses from the sheer fact of *HAVING*
bigger pixels, because bigger pixels are a *source* of blur, given the
same sensor area for the same size image!

> As a real, scientific study, this effort fails horribly, to show what
> you were setting out to demonstrate.

No one has ever proved the opposite! Does that mean nothing to you?
Yet, you apparently accept the opposite as a fact which I need
indisputable proof to disprove!

> Designing of valid experiments is not something easily done. Unless
> you're really skilled in that, you should accept that your efforts may
> be in vain.

All so-called evidence of the inferiority of high pixel density that I've
seen is far less scientific, and far fuller of possible holes than mine.
An intelligent and informed critic should be able to assess exactly what
it is that may be unequal, and have an idea what kind of variance could
be expected, but most of the people here have no experience with the
issues of noise and RAW data, other than what they see in their JPEGs and
conversions, often viewed a 100%, so their experience is not sufficient
to help them in any useful critical thinking.

The basic problem, I think, is that people have big problems, in general,
with the differences between relatives and absolutes, and have their
thoughts warped by using the wrong one in context.

This is a demonstration of the difference between the sensitivity and to
a lesser extent, the resolution of pixels of extreme density difference,
to address the assumption held by most (though their number is
decreasing) that higher pixel density means more noise. I did not pick a
dog for the DSLR contender! I picked one with a pixel-level read noise
only about 1/3 stop higher than the 1D2, very similar quantum efficiency
a difference which would be eradicated by the differences in pixel pitch,
anyway (the 1D3 would have just as much read noise volume, the same shot
noise volume, although this is a read-noise dominated range, and have
less resolution in this test).

--

<>>< ><<> ><<> <>>< ><<> <>>< <>>< ><<>
John P Sheehy <JPS(a)no.komm>
><<> <>>< <>>< ><<> <>>< ><<> ><<> <>><
From: John O'Flaherty on
On Sat, 19 Jul 2008 00:37:19 GMT, John Sheehy <JPS(a)no.komm> wrote:

>Steve <steve(a)example.com> wrote in
>news:r14084pd0bfcgb14qej7eiquttaua3f4tn(a)4ax.com:
>
>> On Thu, 17 Jul 2008 22:15:06 GMT, John Sheehy <JPS(a)no.komm> wrote:
>
>>>That makes no sense at all. I am not comparing cameras; I am comparing
>>>the effects of pixel density. I am fighting the myth that pixel noise
>
>> Actually, you're not doing that at all. What you are doing is
>> comparing the effects of resolution at the focal plane. No one can
>> argue that higher pixel density gives higher resolution at the focal
>> plane. And that's the only thing your test proves ... the obvious.
>> Only you can argue that this somehow translates to higher pixel
>> density gives better noise and DR performance in any real world image.
>> It doesn't, and the rest of the world knows that to be true no matter
>> how much you profess otherwise.
>
>I don't know what to say to you; you are being totally illogical. Can
>you find *any* way in which the 400D crop is less noisy than the FZ50
>one?
>
>I don't know what it is, but I can not for the life of me figure out how
>people can hold such unrealistic models in their heads. Then again, I'm
>the guy who got 100% on all his math and most of his science tests,
>without studying, so maybe I'm expecting too much.
>
>My FZ50 crop shows what the resolution and noise would look like with the
>same exposure, same scene, etc, etc, with FZ50 pixels filling the same
>area of the 400D sensor that its bigger pixels now fill. How do the
>small FZ50 pixels not have less noise?

I did try measuring an area of the sky (which presumably has uniform
illumination) in photoshop histogram, and found a pixel level of about
45 and a standard deviation of about 22, on both magnified images.
Does that mean an equal p-p noise level, but with the noise on the
higher resolution image at higher spatial frequencies?
--
John