Photocopying – Projection printing and copying cameras – Identifying – composing – or selecting
Patent
1992-08-26
1994-05-10
Wintercorn, Richard A.
Photocopying
Projection printing and copying cameras
Identifying, composing, or selecting
355 77, 355133, G03B 2752
Patent
active
053112466
ABSTRACT:
A control area is imaged on photo-sensitive graphic arts material to be evaluated for the sharpness of images printed on the material through the various stages of the reproduction process. The control area includes a light transmitting image divided into a plurality of segments where the image is a sharp-edged line element of a fixed preselected width. The line element is repeated from segment to segment in a preselected pattern of line elements separated a preselected distance apart by a space. The first segment of a control area has a solid optical density. At the opposite end of the control area is positioned a second segment having a substrate optical density. An intermediate segment includes a plurality of sections in which the line elements in each section are spaced apart the same distance, and the spacing between line elements varies from one section to the next. Thus, a range of spatial frequencies of repeating line elements is provided in the control area. By using an integrating densitometer, the optical density at any section at a desired frequency below the solid optical density is measured. At the desired frequency, a theoretical optical density is calculated. The ratio of the theoretical integrated optical density to the measured integrated optical density provides an index of acutance which is 1.0 for a perfectly image line element. If the index is unacceptable, the width of the line element is altered by a calculated correction factor to achieve an acceptable index of acutance.
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Stanton Anthony P.
Warner Richard D.
Graphic Arts Technical Foundation
Price, Jr,. Stanley J.
Wintercorn Richard A.
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