Image compression based on pattern fineness and edge presence
Patent 5374958 Issued on December 20, 1994. Estimated Expiration Date: 
June 25, 2013. 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.
June 25, 2013. 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 ReferencesEncoder capable of faithfully and adaptively encoding a moving image 4920426 Adaptive transform encoder for digital image signal in recording/reproducing apparatus Orthogonal transform coding apparatus for reducing the amount of coded signals to be processed and transmitted Encoding apparatus Patent #: 5150208 InventorAssigneeApplicationNo. 081196 filed on 06/25/1993US Classes:375/240.04, Feed forward375/240.24Block codingExaminersPrimary: Chin, Tommy P.Assistant: Lee, Richard Attorney, Agent or FirmForeign Patent References
International ClassesH04N 007/130H04N 007/133 Foreign Application Priority Data1992-06-30 JPAbstractAlternating current coefficients in a block of orthogonal transform coefficients representing a digital image are quantized with a quantization step size selected with regard to whether the block represents motion or a still image, the fineness of the pictorial pattern in the image, the position of the coefficients in the block, and whether the coefficients represent luminance or chrominance information in the image. The fineness of the pictorial pattern is determined in accordance with the number of alternating current coefficients that exceed a first relatively small threshold value. If any of the alternating current coefficients exceed a second relatively large threshold value, the block is considered to have a high activity, that is, a fine pattern, and so is quantized with a large quantization step.Other References
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