Perceptual image coding by standard-constraint codecs

A perceptual image compression codec exploits the characteristics of the human senses to minimize the perceivable quality loss of digital images under compression. Such a codec has an even higher value if the resulting code-streams are compatible to an existing standard, and are thus decode-able by all-day, existing applications. This work describes strategies how to implement perceptual coding in standardized environments, namely JPEG, JPEG 2000 and JPEG-XR.

I. Introduction

The market success of an image compression scheme not only depends on its compression performance and its features; it also depends on purely non-technical issues, such as standardization and acceptance of the format by manufacturers and consumers: almost twenty years after its standardization, the traditional JPEG[1] scheme is still the predominant image compression codec in consumer applications. While JPEG 2000[4], [6] became not very popular in the consumer market, it is nevertheless accepted in medical imaging and digital cinema applications where better compression performance, higher bit-depths and scalability are of concern. The target application of JPEG-XR[2], based on the HDPhoto codec proposed by Microsoft for standardization by the ISO, is that of high-dynamic range photography, regions where the 1.6 magnitudes offered by the 8 bits/pixel sRGB space is no longer sufficient.