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Digital P&S and color bit depth

 
 
David J Taylor
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      10-27-2006
http://www.velocityreviews.com/forums/(E-Mail Removed) wrote:
[]
> You can read about the DMR here:
> http://www.leica-camera.us/photograp...gital-modul-r/
>
> The DMR uses a Kodak KAF-10010 CCD image sensor. From the data
> sheet, the sensor has a dynamic range of 67 dB. If I remember my
> signal processing facts, that corresponds to a hair over 11 bits.
> The data sheet is here:
> http://www.kodak.com/ezpres/business...10LongSpec.pdf
>
> BTW, the Lecia M8 uses a newer KAF-10050 sensor. It has a dynamic
> range of 76 dB, almost 13 bits. The M8 is on dpreview:
> http://www.dpreview.com/reviews/spec...a/leica_m8.asp


Thanks for that - the M8 is a very nice-looking piece of kit, but the DMR
would not suit me at all. Nothing on the ADC bit-depth, though.

Interesting data sheet as well.

David


 
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Xiaoding
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      10-27-2006
Steves Digicams lists bit depth under "Image Format" on the spec page
for any particular camera. An easy find.

However, I note the poster is into woodworking, which would explain a
lot.

Not everyone is a net geek. and bit depth is an arcane subject, not
one the manufacturers like to talk about much, since all bayer sensors
are essentially the same, which is to say, they suck at color. What
is "of artistic merit"? Why does bit depth have anything to do with
that?

 
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AAvK
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      10-27-2006
Xiaoding wrote:
> Steves Digicams lists bit depth under "Image Format" on the spec page
> for any particular camera. An easy find.


Thanks for the reminder, I did think of checking there but never
got around to it.

> However, I note the poster is into woodworking, which would explain a
> lot.


It is a newer hobby of chisels and hand planes, hand saws
workbenches made for woodworking... making wooden
bellows cameras? I am no expert, much more into photography
and 2D graphics.

> Not everyone is a net geek. and bit depth is an arcane subject, not
> one the manufacturers like to talk about much, since all bayer sensors
> are essentially the same, which is to say, they suck at color. What
> is "of artistic merit"? Why does bit depth have anything to do with
> that?


Why is it arcane as a subject? The bigger those numbers the
more color there will be, right? Try to imagine the Canon D1
(if you know those specs) with 42 or 48 bit color depth, might
be quite awesome images from it (hypathetical). I think the Fuji
film D-SLRs put out a 42 bit raw file!

That's what I mean by the artistic thing, "a higher wealth of
color capability". The more the better for a D-P&S! Even then,
the better the B&W would be from Photoshop.

--
}<)))*> Giant_Alex
cravdraa_at-yahoo_dot-com
not my site: http://www.e-sword.net/

 
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Xiaoding
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      10-27-2006

> Why is it arcane as a subject? The bigger those numbers the
> more color there will be, right? Try to imagine the Canon D1
> (if you know those specs) with 42 or 48 bit color depth, might
> be quite awesome images from it (hypathetical). I think the Fuji
> film D-SLRs put out a 42 bit raw file!
>
> That's what I mean by the artistic thing, "a higher wealth of
> color capability". The more the better for a D-P&S! Even then,
> the better the B&W would be from Photoshop.
>
> --
> }<)))*> Giant_Alex
> cravdraa_at-yahoo_dot-com
> not my site: http://www.e-sword.net/


I though thats what you were getting at. I agree, more bit depth is
needed, but it's more complicated than that.

For one thing, about 1/3 of the bit depth is useless, on the dark end
of the color. More bits help with that, giving you more upper end bits
to work with.

But the big sticking point is color interpolation, a "feature" of bayer
sensors. You do not get real-world, true pixel per pixel color from a
bayer sensor. Instead, you get an estimate, based on whatever
algorythm the camera maker uses, of the real color. The computer in
the camera fills in the blank spots with it's guess of what color was
really in that pixel. Unlike, say, slide film. Bayer sensors do not
have true color, the dif. color pixels are dispersed in a pattern.

Which is why I now shoot slide film now, and scan it in with a Nikon
Coolscan 5000. True color, because the scanner scans every color for
every pixel by stepping across the film. I can't stand digital color,
it's so blah. Nothing beats the black you get from slide film, either!
The trade off is a lack of sharpness, cause digital is sharp, got to
give it that. But I find a few sharpenings with a photo editor gets
pretty close. A full scan, from the Nikon scanner, yields a 131mb
file, from a 35mm slide. I find 5mb is ok for 4x6's. And you get real
bokeh back, too! So that's how I solved my artistic problem, I was not
happy with digital at all. In five years or so, that might change, new
sensors coming online.

 
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ASAAR
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      10-28-2006
On 27 Oct 2006 09:57:08 -0700, Xiaoding wrote:

> Which is why I now shoot slide film now, and scan it in with a Nikon
> Coolscan 5000. True color, because the scanner scans every color for
> every pixel by stepping across the film. I can't stand digital color,
> it's so blah. Nothing beats the black you get from slide film, either!
> The trade off is a lack of sharpness, cause digital is sharp, got to
> give it that. But I find a few sharpenings with a photo editor gets
> pretty close. A full scan, from the Nikon scanner, yields a 131mb
> file, from a 35mm slide. I find 5mb is ok for 4x6's. And you get real
> bokeh back, too! So that's how I solved my artistic problem, I was not
> happy with digital at all. In five years or so, that might change, new
> sensors coming online.


Just a question about your mention of bokeh. Isn't that a
function of the lens? Meaning, whether used on a digital or film
camera, wouldn't the bokeh be the same?

 
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Ed Ruf (REPLY to E-MAIL IN SIG!)
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      10-28-2006
On 27 Oct 2006 09:57:08 -0700, in rec.photo.digital "Xiaoding"
<(E-Mail Removed)> wrote:


>But the big sticking point is color interpolation, a "feature" of bayer
>sensors. You do not get real-world, true pixel per pixel color from a
>bayer sensor. Instead, you get an estimate, based on whatever
>algorythm the camera maker uses, of the real color. The computer in
>the camera fills in the blank spots with it's guess of what color was
>really in that pixel. Unlike, say, slide film. Bayer sensors do not
>have true color, the dif. color pixels are dispersed in a pattern.


I believe that even in film the grains on the emulsion are not omnicolored.

>. And you get real
>bokeh back, too! So that's how I solved my artistic problem, I was not
>happy with digital at all. In five years or so, that might change, new
>sensors coming online.


Sound like you are comparing 35mm film to P&S digitals, not dslrs.

--
Ed Ruf ((E-Mail Removed))
http://edwardgruf.com/Digital_Photog...ral/index.html
 
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Ed Ruf (REPLY to E-MAIL IN SIG!)
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      10-28-2006
On 26 Oct 2006 04:58:38 -0700, in rec.photo.digital "AAvK"
<(E-Mail Removed)> wrote:

>However, it is now well understood that if a camera produces a genuine
>raw file that right off the ccd, it will be 10 or 12 bit color depth as
>a
>single channel (not three rgb), as stated by dpreview. What else can
>we about it besides that?


If you looked at the basic source of the signal in almost all accounts it
is a 12 bit A/D converter.
--
Ed Ruf ((E-Mail Removed))
http://edwardgruf.com/Digital_Photog...ral/index.html
 
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Ed Ruf (REPLY to E-MAIL IN SIG!)
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      10-28-2006
On 27 Oct 2006 08:05:42 -0700, in rec.photo.digital "AAvK"
<(E-Mail Removed)> wrote:


>Why is it arcane as a subject? The bigger those numbers the
>more color there will be, right? Try to imagine the Canon D1
>(if you know those specs) with 42 or 48 bit color depth, might
>be quite awesome images from it (hypathetical). I think the Fuji
>film D-SLRs put out a 42 bit raw file!


I believe you are confusing bit depth with dynamic range. Just what is a
film D-SLR? Seems to be an oxymoron.
--
Ed Ruf ((E-Mail Removed))
http://edwardgruf.com/Digital_Photog...ral/index.html
 
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ASAAR
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      10-28-2006
On Fri, 27 Oct 2006 21:01:45 -0400, Ed Ruf (REPLY to E-MAIL IN
SIG!) wrote:

> I believe you are confusing bit depth with dynamic range. Just what is a
> film D-SLR? Seems to be an oxymoron.


Nope, nothing like that, if I might assume what AAvK meant by
that. Their film SLRs are Fujifilm SLRs, and their DSLRs are
Fujifilm DSLRs. If you look on Fuji product packaging, manuals and
on their website, the company is actually FUJIFILM. From my P&S
digital manual and brochure here's more than anyone but kinga needs:
(actually if anyone has all this, he's probably the one <g>)

> Product Name: FUJIFILM DIGITAL CAMERA FinePix S5100 / FinePix S5500
> Manufacture’s Name: Fuji Photo Film Co., Ltd.
> Manufacture’s Address: 26-30, Nishiazabu 2-chome, Minato-ku,
> Tokyo 106-8620, Japan
> For more information on the full range of Fujifilm digital products,
> please visit our Website: http://home.fujifilm.com


 
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Roger N. Clark (change username to rnclark)
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      10-28-2006
Xiaoding wrote:
>>Why is it arcane as a subject? The bigger those numbers the
>>more color there will be, right? Try to imagine the Canon D1
>>(if you know those specs) with 42 or 48 bit color depth, might
>>be quite awesome images from it (hypathetical). I think the Fuji
>>film D-SLRs put out a 42 bit raw file!
>>
>>That's what I mean by the artistic thing, "a higher wealth of
>>color capability". The more the better for a D-P&S! Even then,
>>the better the B&W would be from Photoshop.
>>
>>--
>>}<)))*> Giant_Alex
>>cravdraa_at-yahoo_dot-com
>>not my site: http://www.e-sword.net/

>
>
> I though thats what you were getting at. I agree, more bit depth is
> needed, but it's more complicated than that.
>
> For one thing, about 1/3 of the bit depth is useless, on the dark end
> of the color.


I disagree with this statement. One needs to process the data
to display/print it, but it is not useless.

> More bits help with that, giving you more upper end bits
> to work with.


If you expose correctly. I still find it strange that people
with film experience continue to complain about dynamic range
of digital when digital has a much higher dynamic range than
film, print or slide. Learn to use your light meter correctly
for the medium. Just like print film must be exposed
differently than slide film, digital is different from either.

> But the big sticking point is color interpolation, a "feature" of bayer
> sensors. You do not get real-world, true pixel per pixel color from a
> bayer sensor.


And neither does your eye. You eye is like a Bayer sensor too!

Then, what is true color? If you read how the eye works, you would
find it is actually impossible for film or digital to produce
accurate colors we see, because our eye is non-linear and subtracts
color from different receptors. What is amazing is that color
works as well as it does. There are whole books written on this
subject.

> Instead, you get an estimate, based on whatever
> algorythm the camera maker uses, of the real color. The computer in
> the camera fills in the blank spots with it's guess of what color was
> really in that pixel.


Digital cameras also use a blur filter, which acts to spread the
light from one spot in the image over the RGB pixels. This averaging
helps to equalize the discrete colored pixels to give better
color reproduction.

> Unlike, say, slide film. Bayer sensors do not
> have true color, the dif. color pixels are dispersed in a pattern.


And film has true color? Light entering the film emulsion is
subject to scattering and absorption by the dye clouds. If you actually
looked up tests of color accuracy of film and digital, you would
find that the digital cameras are consistently better at color accuracy
than any film.

> Which is why I now shoot slide film now, and scan it in with a Nikon
> Coolscan 5000. True color, because the scanner scans every color for
> every pixel by stepping across the film.


You think slide film is true color?

> I can't stand digital color,
> it's so blah.


Ah, now we see! You don't actually want "true" color. You want
vivid color. That's not true color.

> Nothing beats the black you get from slide film, either!


Sorry, but your wrong again. You can dig deeper into shadows and
dark areas with digital, and produce much smoother blacks than any
slide film. Learn to process your digital images. Film has a toe to
it characteristic curve, digital camera images do not. Add a toe in
your photo editor with the curves tool.

> The trade off is a lack of sharpness, cause digital is sharp, got to
> give it that. But I find a few sharpenings with a photo editor gets
> pretty close.


Most photo editors do not have any actual sharpening tools (photoshop
does not). Tools like unsharp mask do not sharpen, they change
accutance.

> A full scan, from the Nikon scanner, yields a 131mb
> file, from a 35mm slide. I find 5mb is ok for 4x6's. And you get real
> bokeh back, too! So that's how I solved my artistic problem, I was not
> happy with digital at all. In five years or so, that might change, new
> sensors coming online.


This might be a statement from 5 years ago. It hasn't been true for years.
One can scan a piece of film at any megapixel you want. I've done
11,000 dpi drum scans of 35mm Velvia, and guess what? There is no
more information than at 6,000 ppi. Consensus by many photographers
is that around 8 megapixels, DSLRs equal or beat 35mm ISO 100 slide film
in terms of resolution.

Some references relevant to the OP and this response:
http://www.clarkvision.com/imagedeta....summary1.html

Dynamic Range and Transfer Functions of Digital Images
and Comparison to Film
http://www.clarkvision.com/imagedetail/dynamicrange2

Digital Cameras: Does Pixel Size Matter?
Factors in Choosing a Digital Camera
http://www.clarkvision.com/imagedeta...el.size.matter

Roger
Photos, digital info at: http://www.clarkvision.com
 
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