An Analysis of Contemporary JPEG2000 Codecs for Image Format Migration

This paper presents results of an analysis of different implementations of the JPEG2000 standard, specifically part 1: JP2, an image format that is currently popular within the digital preservation community. In particular we are interested in the effect different JPEG2000 codecs (encoders and decoders) have on image quality in response to lossy compression. We focus on three main codec libraries for analysis Kakadu, JasPer and OpenJPEG migrating 932 TIFF newspaper images to lossy JPEG2000 files using 2:1 and 4:1 compression ratios, and monitor image quality using PSNR. We look at the combination of encoder/decoder pairs and find that using OpenJPEG for both gives the best quality results, albeit with the slowest execution time. We also find that in some circumstances, particularly when a JasPer encoder is used, in order to retain image quality of the decoded image, the best choice of decoder may not be the same codec used to create the JPEG2000; based on these results, the encoding library is therefore recommended technical preservation metadata to retain.