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:
Aug. 20, 1996
Filed:
Jun. 06, 1995
James J Appel, Rochester, NY (US);
Daniel H Greene, Sunnyvale, CA (US);
J Craig Mudge, Palo Alto, CA (US);
Xerox Corporation, Stamford, CT (US);
Abstract
In order to correct for keystoning distortion when projecting a transparency onto a projection screen, computer software is used to deliberately distort an electronic image. A transparency, which can be a slide or a projection panel display such as an LCD panel, is then produced with the intentionally distorted image. The oblique angle between the horizontal plane through the projector and the viewing screen is compensated for by an inverse tapered compression of the electronic image. In one embodiment, a test slide is generated with a plurality of non parallel line pairs, each line pair representing a different distortion correction to an image. The test slide is projected to the screen to be used. A pair of line pairs most parallel to each other is identified. The line pair identification is used to activate the portion of software which generates that particular image distortion. In another embodiment, focus distortion is corrected by placing the transparency on an easel whose angle, relative to the horizontal, is adjustable. The angle of final projection is selected to obtain optimum focus on the screen.