Post processing transform coded images using edges

Author

Lynch, William E. ; Reibman, Amy R. ; Liu, Bede

Author_Institution

Dept. of Electr. & Comput. Eng., Concordia Univ., Montreal, Que., Canada

Volume

4

fYear

1995

fDate

9-12 May 1995

Firstpage

2323

Abstract

Discrete cosine transform coding, a popular image compression strategy, results in two visible artifacts: blocking and ringing. These are both high frequency artifacts. Since images contain high frequency information the artifacts are removed using a space varying low pass filter as a post processor. Low frequency blocks and flat regions of blocks containing a strong edge are filtered. Low frequency blocks are identified in the transform coefficient domain; edge blocks are identified in the spatial domain. This does not require any alterations in the compressed bit stream. Improvement is demonstrated both subjectively and objectively

Keywords

data compression; discrete cosine transforms; filtering theory; image coding; low-pass filters; transform coding; DCT; blocking; compressed bit stream; discrete cosine transform; edge blocks; flat regions; high frequency artifacts; high frequency information; image compression; low frequency blocks; objective results; post processing; post processor; ringing; space varying low pass filter; spatial domain; subjective results; transform coded images; transform coding; transform coefficient domain; Attenuation; Discrete cosine transforms; Discrete transforms; Filtering; Frequency; Image coding; Image reconstruction; Low pass filters; Nonlinear filters; Streaming media; Transform coding;

fLanguage

English

Publisher

ieee

Conference_Titel

Acoustics, Speech, and Signal Processing, 1995. ICASSP-95., 1995 International Conference on

Conference_Location

Detroit, MI

ISSN

1520-6149

Print_ISBN

0-7803-2431-5

Type

conf

DOI

10.1109/ICASSP.1995.479957

Filename

479957