Title :
Fractal image compression with region-based functionality
Author :
Belloulata, Kamel ; Konrad, Janusz
Author_Institution :
Moncton Univ., NB, Canada
fDate :
4/1/2002 12:00:00 AM
Abstract :
Region-based functionality offered by the MPEG-4 video compression standard is also appealing for still images, for example to permit object-based queries of a still-image database. A popular method for still-image compression is fractal coding. However, traditional fractal image coding uses rectangular range and domain blocks. Although new schemes have been proposed that merge small blocks into irregular shapes, the merging process does not, in general, produce semantically-meaningful regions. We propose a new approach to fractal image coding that permits region-based functionalities; images are coded region by region according to a previously-computed segmentation map. We use rectangular range and domain blocks, but divide boundary blocks into segments belonging to different regions. Since this prevents the use of standard dissimilarity measure, we propose a new measure adapted to segment shape. We propose two approaches: one in the spatial and one in the transform domain. While providing additional functionality, the proposed methods perform similarly to other tested methods in terms of PSNR but often result in images that are subjectively better. Due to the limited domain-block codebook size, the new methods are faster than other fractal coding methods tested. The results are very encouraging and show the potential of this approach for various internet and still-image database applications
Keywords :
data compression; discrete cosine transforms; fractals; image coding; image segmentation; transform coding; visual databases; DCT; Internet; MPEG-4 video compression standard; PSNR; codebook size; coded region; discrete cosine transform; domain blocks; fractal image coding; fractal image compression; irregular shapes; merging process; object-based queries; rectangular range blocks; region-based functionality; segmentation map; spatial domain; standard dissimilarity measure; still-image compression; still-image database; transform domain; Fractals; Image coding; Image databases; Image segmentation; MPEG 4 Standard; Measurement standards; Merging; Shape measurement; Testing; Video compression;
Journal_Title :
Image Processing, IEEE Transactions on
DOI :
10.1109/TIP.2002.999669