RGBE vs Modified TIFF for Encoding High Dynamic Range

Jakkarin Singnoo, Graham D. Finlayson
University of East Anglia, UK
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High Dynamic Range (HDR) imaging has become more widespread in consumer imaging in the past few years, due to the emergence of methods for the recovering HDR radiance maps from multiple photographs. In the domain of HDR encoding, the RGBE radiance format (.hdr) is one of the most widely used. However, conventional image editing applications do not always support this encoding and those that do take considerable time to read or write HDR images (compared with more conventional formats) and this hinders workflow productivity. In this paper we propose a simple, fast, and practical framework to extend the conventional 12 and 16-bit/channel integer TIFF gamma-encoded image format for storing such a wide dynamic range. We consider the potential of our framework for the tone-mapping application both by measuring the ΔE S-CIELAB color difference between original and encoded image, and by conducting a psychophysical experiment to evaluate the perceptual image quality of the proposed framework and compare it with an RGBE radiance encoding. The preliminary results show that our encoding frameworks work well for all images of a 65 image dataset, and give equivalent results compared to RGBE radiance formats, while both consuming much less computational cost and removing the need for a separate image coding format. The results suggest that our method, used in the normal tone mapping workflow, is a good candidate for HDR encoding and could easily be integrated with the existing TIFF image library.