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Electrical and Computer Engineering Commons

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Other Electrical and Computer Engineering

Portland State University

Theses/Dissertations

1997

Articles 1 - 2 of 2

Full-Text Articles in Electrical and Computer Engineering

Optimal Block Encoding And Optimal Entropy For Lossless Image Compression, Larry Ray Dennis Dec 1997

Optimal Block Encoding And Optimal Entropy For Lossless Image Compression, Larry Ray Dennis

Dissertations and Theses

In this thesis, a novel approach is designed using a quad-tree stack structure to encode the image to determine the optimal block size at the optimal and effective entropy in the lossless image compression method. Proof is given through encoding of the predictor and randomly constructed planes. There is a high degree of relationship between the placement of bits in the planes. Clearly results shows that use of the optimal entropy and encoding block sizes will increase the compression ratio using the lossless method. The cost of using the block size methods to encoding and entropy is discussed and proven. …


A Simplified Approach To Reduce Blocking And Ringing Artifacts In Transform-Coded Images, Jianping Hu Feb 1997

A Simplified Approach To Reduce Blocking And Ringing Artifacts In Transform-Coded Images, Jianping Hu

Dissertations and Theses

Presently Block-based Discrete Cosine Transform (BDCT) image coding techniques are widely used in image and video compression applications such as JPEG and MPEG. At a moderate bit rate, BDCT is usually a quite satisfactory solution to most of practical coding applications. However, for high rate compression it produces noticeable blocking and ringing artifacts in the decompressed image. It has been an active research area for a decade for reducing these artifacts. In this thesis, a novel post-processing algorithm is proposed to remove the blocking and ringing artifacts at low bit rate. It is non-iterative and uses both spatial and transform …