Performance of Block Cosine Image Coding with Adaptive Quantization

James W. Modestino, Nariman Farvardin, Michael A. Ogrinc

Research output: Contribution to journalArticlepeer-review

8 Scopus citations


Quantizers for block transform image coding systems are typically designed under the assumption of Gaussian statistics for the transform coefficients. While convincing arguments can be provided in support of this approach, empirical evidence is presented demonstrating that, except possibly for the dc term, wide departures from Gaussian behavior can be expected for real-world imagery at typical block sizes. In this paper we describe the performance of a block cosine image coding system with an adaptive quantizer matched to the statistics of the transform coefficients. The adaptive quantizer is based upon a recently developed algorithm which employs a training sequence in the design procedure. At encoding rates of approximately 1 bit/pixel and above, this approach results in significant improvement in reconstructed image quality compared to fixed quantization schemes designed under the Gaussian assumption. For rates much below 1 bit/pixel the relative improvement is negligible.

Original languageEnglish (US)
Pages (from-to)210-217
Number of pages8
JournalIEEE Transactions on Communications
Issue number3
StatePublished - Mar 1985

ASJC Scopus subject areas

  • Electrical and Electronic Engineering


Dive into the research topics of 'Performance of Block Cosine Image Coding with Adaptive Quantization'. Together they form a unique fingerprint.

Cite this