Digital quality (vs 35mm): Any real answers?

On 23 Jul 2004 19:42:28 -0700, (George Preddy)
wrote:

Roland Karlsson wrote in message ...
Toralf wrote in news:cdrkv0$545
:

OK. I've been thinking a bit about the "luminance" argument that has
popped up a number of times (but not a lot, so I may have overlooked
something), and I'm not sure I'm convinced - although it depends a bit
on how you see it.
... snipped away the rest ...

Your analysis is correct. You cannot detect the color of a small
dot that is just one pixel large with a Bayer sensor. If you have
a Foveon sensor you can. The hue resolution is much higher for
a Foveon (or any other senor that detects all color at each point)
than for Bayer sensor.

But ... that is not as important as it first sounds. To understand
why not there are two things you have to consider:

1. Sampling theory
2. Human vision

Sampling theory states that you must filter away all frequencies
at half the sampling frequency and higher to be able to make an
accurate reproduction of the incoming signal. This filter is
called an anti alias filter and it smooths the incoming signal over
nearby detectors, thus removing the problem with single pixel input.
You simply don't have any single pixel input to detect in the first
place. Some choose to call this a blur filter And - in some sense
it is - but it is neccessary to avoid strange artefacts in the picture.
If you have a sharp lens that is well focussed, you se lots of strange
things in a picture taken without an anti alias filter, e.g. a Sigma

Sigma cameras do NOT sample color. They are the worlds only direct
image sensors. Phenomenally better per pixel image quality than Leaf,
but slightly lower resolution at only 13.72MP.

yes they do, as do all digital devices. They just happen to sample at
3 sites per pixel (but not as accurately as single photosite pixels)

GK

camera.

Human vision has very poor color resolution.

If that was true than no one couldn't see the difference in either of
these scientific test images, where the 13.72MP Foveon displays more
than double the full color resoution of the 6MP Canon 10D ...

http://www.outbackphoto.com/artofraw/raw_05/essay.html
http://www.pbase.com/canon10d_sigmasd9

(George Preddy) writes:

Roland Karlsson wrote in message ...
Toralf wrote in news:cdrkv0$545
:

OK. I've been thinking a bit about the "luminance" argument that has
popped up a number of times (but not a lot, so I may have overlooked
something), and I'm not sure I'm convinced - although it depends a bit
on how you see it.
... snipped away the rest ...

Your analysis is correct. You cannot detect the color of a small
dot that is just one pixel large with a Bayer sensor. If you have
a Foveon sensor you can. The hue resolution is much higher for
a Foveon (or any other senor that detects all color at each point)
than for Bayer sensor.

But ... that is not as important as it first sounds. To understand
why not there are two things you have to consider:

1. Sampling theory
2. Human vision

Sampling theory states that you must filter away all frequencies
at half the sampling frequency and higher to be able to make an
accurate reproduction of the incoming signal. This filter is
called an anti alias filter and it smooths the incoming signal over
nearby detectors, thus removing the problem with single pixel input.
You simply don't have any single pixel input to detect in the first
place. Some choose to call this a blur filter And - in some sense
it is - but it is neccessary to avoid strange artefacts in the picture.
If you have a sharp lens that is well focussed, you se lots of strange
things in a picture taken without an anti alias filter, e.g. a Sigma

Sigma cameras do NOT sample color. They are the worlds only direct
image sensors. Phenomenally better per pixel image quality than Leaf,
but slightly lower resolution at only 13.72MP.

Sorry, this is incorrect. Sigma cameras measure color within bounded
areas at specific points in the image -- which is precisely what
"sampling" means in this context.
--
David Dyer-Bennet, , http://www.dd-b.net/dd-b/
RKBA: http://noguns-nomoney.com/ http://www.dd-b.net/carry/
Pics: http://dd-b.lighthunters.net/ http://www.dd-b.net/dd-b/SnapshotAlbum/
Dragaera/Steven Brust: http://dragaera.info/

(George Preddy) writes:

Roland Karlsson wrote in message ...
Toralf wrote in news:cdrkv0$545
:

OK. I've been thinking a bit about the "luminance" argument that has
popped up a number of times (but not a lot, so I may have overlooked
something), and I'm not sure I'm convinced - although it depends a bit
on how you see it.
... snipped away the rest ...

Your analysis is correct. You cannot detect the color of a small
dot that is just one pixel large with a Bayer sensor. If you have
a Foveon sensor you can. The hue resolution is much higher for
a Foveon (or any other senor that detects all color at each point)
than for Bayer sensor.

But ... that is not as important as it first sounds. To understand
why not there are two things you have to consider:

1. Sampling theory
2. Human vision

Sampling theory states that you must filter away all frequencies
at half the sampling frequency and higher to be able to make an
accurate reproduction of the incoming signal. This filter is
called an anti alias filter and it smooths the incoming signal over
nearby detectors, thus removing the problem with single pixel input.
You simply don't have any single pixel input to detect in the first
place. Some choose to call this a blur filter And - in some sense
it is - but it is neccessary to avoid strange artefacts in the picture.
If you have a sharp lens that is well focussed, you se lots of strange
things in a picture taken without an anti alias filter, e.g. a Sigma

Sigma cameras do NOT sample color. They are the worlds only direct
image sensors. Phenomenally better per pixel image quality than Leaf,
but slightly lower resolution at only 13.72MP.

Sorry, this is incorrect. Sigma cameras measure color within bounded
areas at specific points in the image -- which is precisely what
"sampling" means in this context.
--
David Dyer-Bennet, , http://www.dd-b.net/dd-b/
RKBA: http://noguns-nomoney.com/ http://www.dd-b.net/carry/
Pics: http://dd-b.lighthunters.net/ http://www.dd-b.net/dd-b/SnapshotAlbum/
Dragaera/Steven Brust: http://dragaera.info/

"Justin Thyme" writes:

I don't think we will see 35mm sized imaging chips become the norm. The
cost of production is a lot higher than smaller sensors and always will be.
instead, I think technology improvements will give us lower noise at higher
MP levels in the smaller sensors. Who says a sensor should be the size of
35mm film? remember, 35mm was just a way to make photography a bit cheaper
for the masses, by cutting 70mm film down the centre and hence increasing
the number of photos that any length of film could produce, and as a result
of that it became the standard.

No. 35mm film preceded 70mm film. In the movies. And the 35mm still
frame was created by doubling the 35mm motion picture frame (and
including the margin between the two).

(Which doesn't make your argument any less valid; however it came
about, it's pretty arbitrary.)
--
David Dyer-Bennet, , http://www.dd-b.net/dd-b/
RKBA: http://noguns-nomoney.com/ http://www.dd-b.net/carry/
Pics: http://dd-b.lighthunters.net/ http://www.dd-b.net/dd-b/SnapshotAlbum/
Dragaera/Steven Brust: http://dragaera.info/

"Justin Thyme" writes:

I don't think we will see 35mm sized imaging chips become the norm. The
cost of production is a lot higher than smaller sensors and always will be.
instead, I think technology improvements will give us lower noise at higher
MP levels in the smaller sensors. Who says a sensor should be the size of
35mm film? remember, 35mm was just a way to make photography a bit cheaper
for the masses, by cutting 70mm film down the centre and hence increasing
the number of photos that any length of film could produce, and as a result
of that it became the standard.

No. 35mm film preceded 70mm film. In the movies. And the 35mm still
frame was created by doubling the 35mm motion picture frame (and
including the margin between the two).

(Which doesn't make your argument any less valid; however it came
about, it's pretty arbitrary.)
--
David Dyer-Bennet, , http://www.dd-b.net/dd-b/
RKBA: http://noguns-nomoney.com/ http://www.dd-b.net/carry/
Pics: http://dd-b.lighthunters.net/ http://www.dd-b.net/dd-b/SnapshotAlbum/
Dragaera/Steven Brust: http://dragaera.info/

"David Dyer-Bennet" wrote in message
...
"Justin Thyme" writes:

I don't think we will see 35mm sized imaging chips become the norm. The
cost of production is a lot higher than smaller sensors and always will
be.
instead, I think technology improvements will give us lower noise at
higher
MP levels in the smaller sensors. Who says a sensor should be the size
of
35mm film? remember, 35mm was just a way to make photography a bit
cheaper
for the masses, by cutting 70mm film down the centre and hence
increasing
the number of photos that any length of film could produce, and as a
result
of that it became the standard.

No. 35mm film preceded 70mm film.
Are you sure? according to http://en.wikipedia.org/wiki/35mm_film :
"The origin for the 35 mm size is an Eastman Kodak 70 mm roll film for
photography, being cut in two. "

In the movies. And the 35mm still
frame was created by doubling the 35mm motion picture frame (and
including the margin between the two).

(Which doesn't make your argument any less valid; however it came
about, it's pretty arbitrary.)
Exactly - I don't understand why the constant desire for 35mm full frame
sensors.

"David Dyer-Bennet" wrote in message
...
"Justin Thyme" writes:

I don't think we will see 35mm sized imaging chips become the norm. The
cost of production is a lot higher than smaller sensors and always will
be.
instead, I think technology improvements will give us lower noise at
higher
MP levels in the smaller sensors. Who says a sensor should be the size
of
35mm film? remember, 35mm was just a way to make photography a bit
cheaper
for the masses, by cutting 70mm film down the centre and hence
increasing
the number of photos that any length of film could produce, and as a
result
of that it became the standard.

No. 35mm film preceded 70mm film.
Are you sure? according to http://en.wikipedia.org/wiki/35mm_film :
"The origin for the 35 mm size is an Eastman Kodak 70 mm roll film for
photography, being cut in two. "

In the movies. And the 35mm still
frame was created by doubling the 35mm motion picture frame (and
including the margin between the two).

(Which doesn't make your argument any less valid; however it came
about, it's pretty arbitrary.)
Exactly - I don't understand why the constant desire for 35mm full frame
sensors.

"Justin Thyme" wrote:

Exactly - I don't understand why the constant desire for 35mm full frame
sensors.


It is because people with collections of lenses for 35mm SLRs want to
be able to use them on digital SLRs without a change of angle of view.

"Justin Thyme" wrote:

Exactly - I don't understand why the constant desire for 35mm full frame
sensors.


It is because people with collections of lenses for 35mm SLRs want to
be able to use them on digital SLRs without a change of angle of view.

MXP wrote:
I was surprised how good prints from 35mm Gigabilfilm looked.
I made 20x30cm. No grains at all and super sharp even with a x15 magnifier
directly on
the print. I think more people should try this film.

Very sharp and smooth 20x30CM (or more usually 24x30cm) prints is NORMAL
with just about any non-high speed B&W film, not just Gigabit.

Chris