Browse Prior Art Database

Exposure Control for Microfilming Documents

IP.com Disclosure Number: IPCOM000093396D
Original Publication Date: 1967-Sep-01
Included in the Prior Art Database: 2005-Mar-06
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Boone, JW: AUTHOR [+2]

Abstract

A method of exposure control for use in a multigeneration film system is provided.

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 92% of the total text.

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Exposure Control for Microfilming Documents

A method of exposure control for use in a multigeneration film system is provided.

To determine the proper exposure time for the microfilming operation, the following steps are taken.
1. Scan the original document with a flying spot scanner.
2. Convert the reflectance outputs from the flying spot scanner

to density values.
3. Subtract Dmin to Dmax to provide average print contrast.
4. From the average width of line data obtained on the scan in

Step 1, determine the loss in log exposure due to this line

width by multiplying the ordinate of the point for the average

measured line width by the average print contrast. This loss
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factor is a function of the optical system and the

photographic film and is obtained for the lens-film

combination.
5. Compute the density modulation factor for the document by

subtracting the loss in log exposure due to average line width

from the average print contrast and multiplying the remainder

by a constant factor. This constant factor can be determined

for a given film developed to a specific gamma and the

inflection point of the photomaterial which is used in the

succeeding generation. For average unit gamma development and
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a diazo film in the next generation the factor is .75. The

value obtained above is added to the Dmin value obtained in

Step 3. This is the density modulation factor.
6. Add the density modulation factor obtained in Step 5 to the

zero modulation log e...