The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Mar. 19, 1991
Filed:
Jul. 30, 1990
Applicant:
Inventors:
Yoshinobu Mita, Kawasaki, US;
Naoto Kawamura, Yokohama, US;
Tadashi Yoshida, Ichikawa, US;
Katsuhito Dei, Tokyo, JP;
Assignee:
Canon Kabushiki Kaisha, Tokyo, JP;
Attorney:
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
G06K / ;
U.S. Cl.
CPC ...
382 50 ; 382 54 ; 358163 ; 358455 ; 358461 ; 356404 ; 364722 ;
Abstract
An image reading apparatus has a CCD sensor, a white standard plate of a uniform density, a shading data memory, an analog/log converter or a digital/log converter, and a shading correction circuit. Shading correction can be performed with a simple circuit and requiring only a small-capacity memory.