Fixed rate JPEG compliant still image compression
Patent 5677689 Issued on October 14, 1997. Estimated Expiration Date: 
August 31, 2015. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.
August 31, 2015. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.Patent ReferencesMethod of compressing digital image data and device thereof System for compression and decompression of video data using discrete cosine transform and coding techniques Patent #: 5341318 InventorsApplicationNo. 521789 filed on 08/31/1995US Classes:341/50, DIGITAL CODE TO DIGITAL CODE CONVERTERS382/238, Predictive coding382/250, Discrete cosine or sine transform382/251QuantizationExaminersPrimary: Young, BrianForeign Patent References
International ClassH03M 007/30AbstractThe 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.Other References
|
|
