Frequency modulated acutance guide and method of use

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...

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Bibliographic Details
Main Authors WARNER; RICHARD D, STANTON; ANTHONY P
Format Patent
LanguageEnglish
Published 10.05.1994
Edition5
Subjects
AUXILIARY PROCESSES IN PHOTOGRAPHY
CINEMATOGRAPHY
ELECTROGRAPHY
HOLOGRAPHY
INDEXING SCHEME RELATING TO PRINTING, LINING MACHINES,TYPEWRITERS, AND TO STAMPS
LINING MACHINES
PERFORMING OPERATIONS
PHOTOGRAPHIC PROCESSES, e.g. CINE, X-RAY, COLOUR,STEREO-PHOTOGRAPHIC PROCESSES
PHOTOGRAPHY
PHOTOSENSITIVE MATERIALS FOR PHOTOGRAPHIC PURPOSES
PHYSICS
PRINTING
STAMPS
TRANSPORTING
TYPEWRITERS
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Summary: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.
Bibliography:Application Number: US19920935869