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"digital" flash mode (no actual flash fired) HP945



 
 
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  #11  
Old July 24th 04, 03:19 PM
Michael Meissner
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Default "digital" flash mode (no actual flash fired) HP945

lid writes:

Michael Meissner wrote:

The problem is most digital cameras have a lot less range than print
films do, between dark and light. Slide films have the same sort of
problems, and the solution is typically the same (expose to avoid
burning out the highlights and bring out shadow detail in post
processing). In the most common case of JPEG, there are only 8 bits
(values 0-255) for each color per pixel.


Yeah, but usually those 8 bits represent a value that you raise to the
power 2.2 to get luminance. When you work that out, 8 bits is a heck
of a dynamic range.


The classic counterexample is shooting weddings, and trying to get detail in
both the bride's white dress and the groom's black tux. From what I've read,
most digital cameras give you the range of slide film, but print film still
gives more latitude.

From what I can see, digital sensors (or at least those in DSLRs) have
more dynamic range than transparencies but less than print film. It
may be that with a drum scanner you can squeeze a bit more out of a
transparency.


I believe in general you only get that extended range in DSLRs when you use raw
mode, which for many cameras can give you 10-12 bits of precision. I believe
some of the newer Fujis are trying to address the dynamic range problem by
having two sensors for the high and low values. And even the Sigmas are trying
to attack the problem, its a pity that the implementation leaves a lot to be
desired compared to the theory.

I suspect within 5 years or so, there will be a shift to using 16-bit formats
in cameras. As bragging rights, I would hope the megapixel race is nearly
over, and manufacturers start concentrating on higher ISO values (with less
noise) and more tonality.

--
Michael Meissner
email:

http://www.the-meissners.org
  #12  
Old July 25th 04, 10:58 AM
external usenet poster
 
Posts: n/a
Default "digital" flash mode (no actual flash fired) HP945

Michael Meissner wrote:
lid writes:


Michael Meissner wrote:

The problem is most digital cameras have a lot less range than print
films do, between dark and light. Slide films have the same sort of
problems, and the solution is typically the same (expose to avoid
burning out the highlights and bring out shadow detail in post
processing). In the most common case of JPEG, there are only 8 bits
(values 0-255) for each color per pixel.


Yeah, but usually those 8 bits represent a value that you raise to the
power 2.2 to get luminance. When you work that out, 8 bits is a heck
of a dynamic range.


The classic counterexample is shooting weddings, and trying to get detail in
both the bride's white dress and the groom's black tux.


But that's not really a counterexample: there's no way that the ratio
of tux/dress exceeds the dynamic range of a JPEG encoded at gamma 2.2.
The limiting factor is still sensor noise.

From what I've read, most digital cameras give you the range of
slide film, but print film still gives more latitude.


From what I can see, digital sensors (or at least those in DSLRs)
have more dynamic range than transparencies but less than print
film. It may be that with a drum scanner you can squeeze a bit
more out of a transparency.


I believe in general you only get that extended range in DSLRs when
you use raw mode, which for many cameras can give you 10-12 bits of
precision.


What raw gives you is linear encoding, at least with CCDs. That gives
you an opportunity to use curves somehow to squeeze that huge dynamic
range into that of a print -- which has Dmax 1.2 if you're lucky.

I suspect within 5 years or so, there will be a shift to using
16-bit formats in cameras.


Actively cooled sensors, maybe?

Andrew.
  #13  
Old July 25th 04, 10:58 AM
external usenet poster
 
Posts: n/a
Default "digital" flash mode (no actual flash fired) HP945

Michael Meissner wrote:
lid writes:


Michael Meissner wrote:

The problem is most digital cameras have a lot less range than print
films do, between dark and light. Slide films have the same sort of
problems, and the solution is typically the same (expose to avoid
burning out the highlights and bring out shadow detail in post
processing). In the most common case of JPEG, there are only 8 bits
(values 0-255) for each color per pixel.


Yeah, but usually those 8 bits represent a value that you raise to the
power 2.2 to get luminance. When you work that out, 8 bits is a heck
of a dynamic range.


The classic counterexample is shooting weddings, and trying to get detail in
both the bride's white dress and the groom's black tux.


But that's not really a counterexample: there's no way that the ratio
of tux/dress exceeds the dynamic range of a JPEG encoded at gamma 2.2.
The limiting factor is still sensor noise.

From what I've read, most digital cameras give you the range of
slide film, but print film still gives more latitude.


From what I can see, digital sensors (or at least those in DSLRs)
have more dynamic range than transparencies but less than print
film. It may be that with a drum scanner you can squeeze a bit
more out of a transparency.


I believe in general you only get that extended range in DSLRs when
you use raw mode, which for many cameras can give you 10-12 bits of
precision.


What raw gives you is linear encoding, at least with CCDs. That gives
you an opportunity to use curves somehow to squeeze that huge dynamic
range into that of a print -- which has Dmax 1.2 if you're lucky.

I suspect within 5 years or so, there will be a shift to using
16-bit formats in cameras.


Actively cooled sensors, maybe?

Andrew.
  #14  
Old July 28th 04, 01:57 AM
Michael Meissner
external usenet poster
 
Posts: n/a
Default "digital" flash mode (no actual flash fired) HP945

lid writes:

Michael Meissner wrote:
lid writes:

Michael Meissner wrote:

The problem is most digital cameras have a lot less range than print
films do, between dark and light. Slide films have the same sort of
problems, and the solution is typically the same (expose to avoid
burning out the highlights and bring out shadow detail in post
processing). In the most common case of JPEG, there are only 8 bits
(values 0-255) for each color per pixel.

Yeah, but usually those 8 bits represent a value that you raise to the
power 2.2 to get luminance. When you work that out, 8 bits is a heck
of a dynamic range.


The classic counterexample is shooting weddings, and trying to get detail in
both the bride's white dress and the groom's black tux.


But that's not really a counterexample: there's no way that the ratio
of tux/dress exceeds the dynamic range of a JPEG encoded at gamma 2.2.
The limiting factor is still sensor noise.


You sound like you know more about it than I do, but I do know weddings can
stress most cameras, and usually you have to underexpose digitals so that the
highlights aren't blown.

From what I've read, most digital cameras give you the range of
slide film, but print film still gives more latitude.


From what I can see, digital sensors (or at least those in DSLRs)
have more dynamic range than transparencies but less than print
film. It may be that with a drum scanner you can squeeze a bit
more out of a transparency.


I believe in general you only get that extended range in DSLRs when
you use raw mode, which for many cameras can give you 10-12 bits of
precision.


What raw gives you is linear encoding, at least with CCDs. That gives
you an opportunity to use curves somehow to squeeze that huge dynamic
range into that of a print -- which has Dmax 1.2 if you're lucky.

I suspect within 5 years or so, there will be a shift to using
16-bit formats in cameras.


I was just speculating that if you go past 8 bits of precision, the next format
is 16 bits -- even if you only have 12 bits worth of precision from the camera.

Actively cooled sensors, maybe?


Perhaps.

--
Michael Meissner
email:

http://www.the-meissners.org
 




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