Dynamic Range testing
Dynamic Range testing
- Subject: Dynamic Range testing
- From: "Phil lippincott" <email@hidden>
- Date: Tue, 11 May 2004 18:43:12 -0700
Hi Bob, Doug, Ernst, Jim, Rudy and Terry
After several years of doing scanner Density Range and Optical
Visibility Testing PMA (Photo Marketing Association International) and DIMA
asked for me to assist in "Scanner Round Up" testing for the scanner
industry. The review of the testing criteria and the assistance of conduct
of the tests included about 80 scanners so far and the assistance over the
years of about 15 manufacturers. The testing criteria, a comparison
presentation and some of the results can be reviewed at
www.scannerforum.com
This testing effort has gone for about 14 years.
>
> Date: Fri, 07 May 2004 11:21:40 +0200
>
From: Ernst Dinkla <email@hidden>
>
To: email@hidden
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Subject: Re: Dynamic Range testing
>
>
Jim Rich wrote:
>
>
> On 5/6/04 3:39 PM, "Rudy Harvey" <email@hidden> wrote:
>
>
>
>
>
>>Hi Terry, It was called the Q' Factor.
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>>
>
>>You are correct , it is a very real effect, caused by dispersion of the
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>>light path
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>>by film grain. It is another good reason to scan using oil. Using oil
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>>in effect , reduces
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>>the number of surfaces to 2 instead of 6(mylar-2 , film-2,drum-2)
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>>
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>>Yea, have not heard that mentioned in over 10 years.
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>>I just love terms like this , they only mean something to about 20
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>>people on the planet.
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>>
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>>All the Best
>
>>Rudy Harvey
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>
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> Rudy,
>
>
>
> Since you like those terms, perhaps some on this list might find this
>
> spectrophotmetric tid bit interesting. In the early 1900s (1909) a chap
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> named Callier created a formula for the relationship between specular
>
> density and diffuse density. The formula is called Calliers Q factor.
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>
>
> Jim Rich
>
>
The Callier effect as we called it in relation to the behaviour
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of silver emulsions in point light enlargers versus diffuse light
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enlargers. There still could be a good reason to use a silver
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target in a scanner if it will be used for non-chromogene B&W
>
film. The use of oil will not reduce the true Callier effect but
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can reduce a related effect of a matte film surface.
>
>
Ernst
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