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"16-bit" mode.



 
 
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  #201  
Old November 26th 04, 08:21 AM
Michael Schnell
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Maybe this converts a gamma corrected 12 bit encoding into linear 15 bit
coding.

-Michael




  #202  
Old November 26th 04, 08:21 AM
Michael Schnell
external usenet poster
 
Posts: n/a
Default

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Maybe this converts a gamma corrected 12 bit encoding into linear 15 bit
coding.

-Michael




  #203  
Old November 26th 04, 08:41 AM
Dave Martindale
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writes:

Timo Autiokari wrote:
Exposure adjustment in fact is a linear
operation, multiplication by a factor,


Incorrect. It's scaled in F-stops, which are exponential, not linear.


Exposure adjustment by +1 fstop is the same as multiplication of the
data values by 2. Exposure adjustment by +2 fstop is the same as
multiplication of the data values by 4. So a linear operation. Just
the gradation of the aperture and the time dial is logarithmic, they
both affect to the data linearly.


You failed maths at school, didn't you?


Actually, Timo's right here.

"Linear" is a term that appears all over the place, with somewhat
different meanings. In high school math, linear probably refers to a
first-degree polynomial.

In signal processing, a linear system is one where the result of
applying the system to the sum of two signals is the same as the sum of
applying the system to the two signals individually (superposition).
(These are not the same; the function y = 2x + 3 is a linear
polynomial, but it's *not* linear in the signal processing sense).

And in television, the electronics are linear even though the signal
being processed is non-linearly related to scene brightness.

In this example, exposure adjustment is a linear operator in the signal
processing sense. The amount of adjustment can be specified directly
(2X, 0.5X), or as an equivalent number of stops. F-stops are a
logarithmic scale used to specify (in this case) a linear transformation
scale factor.

You'll find the mathematical details in
any good textbook onphotography.


Then study them.


I have. You clearly havn't.
I won't waste my time trying to educate you, as you clearly prefer to be
ignorant.


You're both arguing past each other, unable to see that each is applying
"linear" to something different.

Dave
  #204  
Old November 26th 04, 08:41 AM
Dave Martindale
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Posts: n/a
Default

writes:

Timo Autiokari wrote:
Exposure adjustment in fact is a linear
operation, multiplication by a factor,


Incorrect. It's scaled in F-stops, which are exponential, not linear.


Exposure adjustment by +1 fstop is the same as multiplication of the
data values by 2. Exposure adjustment by +2 fstop is the same as
multiplication of the data values by 4. So a linear operation. Just
the gradation of the aperture and the time dial is logarithmic, they
both affect to the data linearly.


You failed maths at school, didn't you?


Actually, Timo's right here.

"Linear" is a term that appears all over the place, with somewhat
different meanings. In high school math, linear probably refers to a
first-degree polynomial.

In signal processing, a linear system is one where the result of
applying the system to the sum of two signals is the same as the sum of
applying the system to the two signals individually (superposition).
(These are not the same; the function y = 2x + 3 is a linear
polynomial, but it's *not* linear in the signal processing sense).

And in television, the electronics are linear even though the signal
being processed is non-linearly related to scene brightness.

In this example, exposure adjustment is a linear operator in the signal
processing sense. The amount of adjustment can be specified directly
(2X, 0.5X), or as an equivalent number of stops. F-stops are a
logarithmic scale used to specify (in this case) a linear transformation
scale factor.

You'll find the mathematical details in
any good textbook onphotography.


Then study them.


I have. You clearly havn't.
I won't waste my time trying to educate you, as you clearly prefer to be
ignorant.


You're both arguing past each other, unable to see that each is applying
"linear" to something different.

Dave
  #210  
Old November 26th 04, 05:51 PM
Dave Martindale
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Posts: n/a
Default

writes:

I have no idea whether he has any skill as a photographer, but the
comments I've seen him make on theoretical concepts are totally
clueless. He's not quite as deluded as The Preddiot, but he's in the
same weight-class.


I'd have to disagree with that. I had a number of long drawn-out
arguments with Timo in this newsgroup several years ago, but I have to
say that The Preddiot is worse.

Timo is pretty firmly convinced of his own rightness, and tends to
disparage the personal integrity of anyone who disagrees with him. But
if you argue with him in minute detail about something he says that is
clearly wrong, he will eventually see that. He'll never say "I was
wrong", but he will abandon wrong positions eventually if you prove
he's wrong. It just isn't worth the work to do so.

Timo does care about telling people the truth; it's just that he's
sometimes wrong and it's incredibly hard to demonstrate that to his
satisfaction. He's also put a lot of time and effort into thinking
about image processing and setting up his pages; it's too bad they are
sometimes misleading.

But "George Preddy" just makes ridiculous statements, with no reasonable
argument to back them up. And he won't support what he says - he
ignores questions from other people. He's effectively an output-only
device with no regard for the truth at all. Nor does he seem capable of
much original argument; he mostly just parrots Foveon marketing hype.

Dave
 




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