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:
Oct. 14, 1997
Filed:
Aug. 31, 1995
Gregory S Yovanof, Sunnyvale, CA (US);
Alexander I Drukarev, Los Altos, CA (US);
Other;
Abstract
The present invention is a fully JPEG compliant two-pass approach that can compress an arbitrary image to a predetermined fixed size file. The compression coding device and method according to the present invention estimates an activity metric based on the average sum of the absolute value of the quantized DCT coefficients per block. Given the activity metric, a mathematical model relating the image activity to the JPEG Q-factor for a given value of the target compression ratio provides an estimated Q-factor value that yields the design target ratio. This mathematical model is developed during a calibration phase which is executed once off line for a given image capturing device. The fact that our activity metric is based on the quantized DCT coefficients allows for an efficient implementation of the presented coding method in either speed or memory bound systems.