The darkest black achievable with a top-flight black and white paper, optimally processed, reflects about 1/200 as much light as the pure, paper-base white: a brightness range of 200:1. Few prints will achieve this: a more realistic brightness range is between 100:1 and 125:1. What is more, there is a difference between the total range -- the purest white and deepest black -- and the dynamic range, within which there is texture and detail. This is very unlikely to exceed 100:1, and may well be more like 64:1.
Numbers and diagrams are results of experimenting, and even contain a certain experimental error of about 0.5%..1% (see for example how 18% grey translates into L=49.5 instead of being exact L=50). The text is also based on our experience in coding raw converters. All the conclusions you can easily verify in direct experiments - a camera with a spotmeter, a grey card or a sheet of white paper that does not contain optical brightner, a source of light like a flashgun, a wide dynamic range scene like a landscape in a sunny day, and Rawnalyze software is all that is needed.
Centred exposure is an exposure that places the subject into one of three zones that result in most detailed print. In other words, it is the exposure that is centred on the proper exposure of the subject rather on the preserving extreme highlights. You may want to read the complimentary article Spot-Metering: Reading Adams in Reverse Direction for the suggestions on exposure compensation.
But sometimes, figures and samples speaks more than numbers and diagrams.
Do you have any example to show ?
And if I understand, when you speaks about centered exposure, you mean relying to in camera lightmeter without compensation ?
Thanks in advance
We've choosen another option
- public version of LibRaw is GPLed as includes GPLed code
- we'll offer personalized licenses to any developer (company or person) of specific software. Of course, personalized LibRaw will not contain GPLed Coffin's code.
Roger W. Hicks writes:
The darkest black achievable with a top-flight black and white paper, optimally processed, reflects about 1/200 as much light as the pure, paper-base white: a brightness range of 200:1. Few prints will achieve this: a more realistic brightness range is between 100:1 and 125:1. What is more, there is a difference between the total range -- the purest white and deepest black -- and the dynamic range, within which there is texture and detail. This is very unlikely to exceed 100:1, and may well be more like 64:1.
(http://www.rogerandfrances.com/photoschool/ps%20subject%20brightness%20r...)
Numbers and diagrams are results of experimenting, and even contain a certain experimental error of about 0.5%..1% (see for example how 18% grey translates into L=49.5 instead of being exact L=50). The text is also based on our experience in coding raw converters. All the conclusions you can easily verify in direct experiments - a camera with a spotmeter, a grey card or a sheet of white paper that does not contain optical brightner, a source of light like a flashgun, a wide dynamic range scene like a landscape in a sunny day, and Rawnalyze software is all that is needed.
Centred exposure is an exposure that places the subject into one of three zones that result in most detailed print. In other words, it is the exposure that is centred on the proper exposure of the subject rather on the preserving extreme highlights. You may want to read the complimentary article Spot-Metering: Reading Adams in Reverse Direction for the suggestions on exposure compensation.
But sometimes, figures and samples speaks more than numbers and diagrams.
Do you have any example to show ?
And if I understand, when you speaks about centered exposure, you mean relying to in camera lightmeter without compensation ?
Thanks in advance
We've choosen another option
- public version of LibRaw is GPLed as includes GPLed code
- we'll offer personalized licenses to any developer (company or person) of specific software. Of course, personalized LibRaw will not contain GPLed Coffin's code.
It can be LGPLed with a simple caveat for the GPLed Foveon module.
By the way, I wrote about Libraw before you did it, here :
http://photofeedback.blogspot.com/2007_02_01_archive.html
Edmund
Edmund,
LibRaw uses GPLed Foveon decoder from dcraw.
-- Alex
Libraries should be LGPL licensed -
Edmund
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