title: A joint source-channel distortion model for JPEG compressed images.
abstract: The need for efficient joint source-channel coding (JSCC) is growing as new multimedia services are introduced in commercial wireless communication systems. An important component of practical JSCC schemes is a distortion model that can predict the quality of compressed digital multimedia such as images and videos. The usual approach in the JSCC literature for quantifying the distortion due to quantization and channel errors is to estimate it for each image using the statistics of the image for a given signal-to-noise ratio (SNR). This is not an efficient approach in the design of real-time systems because of the computational complexity. A more useful and practical approach would be to design JSCC techniques that minimize average distortion for a large set of images based on some distortion model rather than carrying out per-image optimizations. However, models for estimating average distortion due to quantization and channel bit errors in a combined fashion for a large set of images are not available for practical image or video coding standards employing entropy coding and differential coding. This paper presents a statistical model for estimating the distortion introduced in progressive JPEG compressed images due to quantization and channel bit errors in a joint manner. Statistical modeling of important compression techniques such as Huffman coding, differential pulse-coding modulation, and run-length coding are included in the model. Examples show that the distortion in terms of peak signal-to-noise ratio (PSNR) can be predicted within a 2-dB maximum error over a variety of compression ratios and bit-error rates. To illustrate the utility of the proposed model, we present an unequal power allocation scheme as a simple application of our model. Results show that it gives a PSNR gain of around 6.5 dB at low SNRs, as compared to equal power allocation.
authors.affiliation: Laboratory for Image and Video Engineering, Department of Electrical and Computer Engineering, The University of Texas at Austin, TX 78712-1084, USA. mfsabir@ece.utexas.edu
authors.forename: Muhammad F
authors.initials: MF
authors.lastname: Sabir
authors.forename: Hamid Rahim
authors.initials: HR
authors.lastname: Sheikh
authors.forename: Robert W
authors.initials: RW
authors.lastname: Heath
authors.forename: Alan C
authors.initials: AC
authors.lastname: Bovik
mesh_terms: D000465:Algorithms; D016477:Artifacts; D003195:Computer Communication Networks; D003196:Computer Graphics; D003198:Computer Simulation; D044962:Data Compression / Q000379:methods*; D003627:Data Interpretation, Statistical; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D015233:Models, Statistical; D012815:Signal Processing, Computer-Assisted