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"Why Raw" Article



 
 
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  #21  
Old September 2nd 05, 07:59 AM
David J Taylor
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Slack wrote:
[]

What is Distiller? I'm always willing to learn new stuff.


http://www.adobe.com/products/acrdis/main.html


  #22  
Old September 2nd 05, 08:25 AM
Andy Dee
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David J Taylor wrote:

Slack wrote:
[]



What is Distiller? I'm always willing to learn new stuff.



http://www.adobe.com/products/acrdis/main.html




Open Office can export to PDF and its free!
A
  #23  
Old September 2nd 05, 09:49 PM
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In message ,
"David J Taylor"

wrote:

wrote:


In therms of luminance, it is actually (255^2.2):1 or 196,965:1.


Thanks, John. Our understanding is the same, then. I only quoted
200,000:1


Sorry; I didn't even notice that you wrote that. I read it fast, and
somehow thought you were writing about 255:1.

simply because if I quoted the exact number I expected someone
to think I was being pedantic! I can appreciate that JPEG might be
optimised in a slightly different way to TIFF so that errors are masked.


By the way (for anyone else who's still reading), this 2.2 gamma figure is
what some cameras call the "contrast" setting - use a smaller number when
converting from linear to JPEG and you'll get more contrast, a larger
number gives less contrast.


Most JPEG conversions, I think, vary the gamma across the histogram.
This is important if you want to keep middle grey standard, but expand
or compress contrast relative to it.

I really wish I had a greyscale wedge the quality of the Gretag-MacBeth
color checker, but with about 10 stops of grey rectangles with steps of
about 1/6 stop, or even a pie wedge to discount light roll-off.
--


John P Sheehy

  #25  
Old September 3rd 05, 08:00 PM
RSD99
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wrote in message
...
In message ,
"David J Taylor"

wrote:

wrote:


In therms of luminance, it is actually (255^2.2):1 or 196,965:1.


Thanks, John. Our understanding is the same, then. I only quoted
200,000:1


Sorry; I didn't even notice that you wrote that. I read it fast, and
somehow thought you were writing about 255:1.

simply because if I quoted the exact number I expected someone
to think I was being pedantic! I can appreciate that JPEG might be
optimised in a slightly different way to TIFF so that errors are masked.


By the way (for anyone else who's still reading), this 2.2 gamma figure

is
what some cameras call the "contrast" setting - use a smaller number

when
converting from linear to JPEG and you'll get more contrast, a larger
number gives less contrast.


Most JPEG conversions, I think, vary the gamma across the histogram.
This is important if you want to keep middle grey standard, but expand
or compress contrast relative to it.

I really wish I had a greyscale wedge the quality of the Gretag-MacBeth
color checker, but with about 10 stops of grey rectangles with steps of
about 1/6 stop, or even a pie wedge to discount light roll-off.
--


John P Sheehy


Re the grayscale you desire ... get a Kodak Q-13 "Kodak Color Separation
Guide and Gray Scale-Small," costs something like US$20 at places such as
B&H.

http://www.bhphotovideo.com/bnh/cont...=1&sq=desc&Ini
tialSearch=yes&O=SearchBar&A=search&Q=*&bhs=t&shs= Kodak+Q-13&image.x=10&ima
ge.y=5

They are literally an "industry standard," and have been used as such for
over fifty years.


  #26  
Old September 4th 05, 12:09 AM
Bart van der Wolf
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"RSD99" wrote in message
news:ApmSe.707$Sx4.18@trnddc06...
SNIP
Re the grayscale you desire ... get a Kodak Q-13 "Kodak Color
Separation Guide and Gray Scale-Small," costs something like
US$20 at places such as B&H.


Unfortunately the range they cover is too small for a decent DSLR.

The one you'll need is e.g. the Stouffer T4110:
http://www.stouffer.net/TransPage.ht...mission%20step

It covers a range of approx. 10000:1 or 13.5 stops. That should be
enough to be able to determine the dynamic range with a single
exposure.

Bart

  #27  
Old September 4th 05, 01:52 AM
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In message ApmSe.707$Sx4.18@trnddc06,
"RSD99" wrote:

Re the grayscale you desire ... get a Kodak Q-13 "Kodak Color Separation
Guide and Gray Scale-Small," costs something like US$20 at places such as
B&H.

http://www.bhphotovideo.com/bnh/cont...=1&sq=desc&Ini
tialSearch=yes&O=SearchBar&A=search&Q=*&bhs=t&shs =Kodak+Q-13&image.x=10&ima
ge.y=5

They are literally an "industry standard," and have been used as such for
over fifty years.


I already have this, and the quality is poor. It is glossy, and they
grey rectangles are reddish. You have to use special lighting for the
glare not to be an issue.
--


John P Sheehy

  #28  
Old September 4th 05, 01:59 AM
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In message ,
"Bart van der Wolf" wrote:


"RSD99" wrote in message
news:ApmSe.707$Sx4.18@trnddc06...
SNIP
Re the grayscale you desire ... get a Kodak Q-13 "Kodak Color
Separation Guide and Gray Scale-Small," costs something like
US$20 at places such as B&H.


Unfortunately the range they cover is too small for a decent DSLR.

The one you'll need is e.g. the Stouffer T4110:
http://www.stouffer.net/TransPage.ht...mission%20step

It covers a range of approx. 10000:1 or 13.5 stops. That should be
enough to be able to determine the dynamic range with a single
exposure.


That looks interesting. Do you have one? Is glare an issue?
--


John P Sheehy

 




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