Title: Efficient DCT-based image compression technique

Authors: Shaimaa A. El-said

Addresses: Electronics and Communications Department, Faculty of Engineering, Zagazig University, P.O. Box 44519, Zagazig, Egypt

Abstract: Although JPEG technique is considered as the most popular image compression standard, it behaves high visual degradation at low bit rates. In this paper, an efficient DCT-based image compression technique is proposed to achieve high Compression Ratio (CR) with high quality at both high and low bit rates. This technique uses switching between JPEG compression technique at high bit rates and a novel Adaptive Lossy Image Compression (ALIC) technique at low bit rates. ALIC is proposed to overcome the drawbacks of JPEG technique at low bitrates. The performance of the proposed technique is analysed at low and high bit rates on both grey and colour images. Performances of both JPEG and ALIC techniques are analysed and compared. The experimental results reveal that the proposed ALIC technique achieves better CR with acceptable SNR in comparison with JPEG technique. Also, the resultant CR of ALIC technique can be considerably increased with a slight decrease of its PSNR. This decrease in PSNR does not result in a noticeable visual degradation of the compressed image. On the other hand, increasing the CR of JPEG technique results in a noticeable visual degradation due to the appearance of blocking effect in the reconstructed image. Thus, it is greatly recommended to use ALIC technique in the applications that require high CR with stable PSNR. ALIC is a general purpose technique that can be applied, not only on images, but also on any data source which uses Huffman coding to achieve better CR. Therefore, it is suitable for compression of text, image and video.

Keywords: adaptive image compression; DCT; discrete cosine transform; lossy compression; huffman encoding; run-length encoding; JPEG compression.

DOI: 10.1504/IJSISE.2013.056637

International Journal of Signal and Imaging Systems Engineering, 2013 Vol.6 No.4, pp.259 - 274

Received: 05 Jan 2011
Accepted: 29 Feb 2012
Published online: 30 Sep 2013 *

Full-text access for editors Full-text access for subscribers Purchase this article Comment on this article