“Subband Encoding of High Dynamic Range Imagery” by Ward, Simmons, Ward and Galoppo

  • ©Greg J. Ward and Maryann Simmons




    Subband Encoding of High Dynamic Range Imagery



    All existing and proposed high dynamic range (HDR) formats yield prohibitively large images that can only be viewed and manipulated by specialized software, which has impeded wider adoption of this technology. In this sketch, we present a simple approach to HDR storage in a backwards-compatible, “lossy” image format. A tone-mapped version of the HDR original is accompanied by restorative information carried in a subband of a standard 24-bit RGB format. This subband contains a compressed ratio image, which when multiplied by the tone-mapped foreground, recovers the HDR original. The tone-mapped image data may also be compressed, permitting the composite to be delivered in a standard JPEG wrapper. To naïve software, the image looks like any other, and displays as a tone-mapped version of the original. To HDR-enabled software, the foreground image is merely a tone-mapping suggestion, as the original pixel data are available by decoding the information in the subband. Errors are visible in only a very small percentage of the pixels after decoding, and the technique requires only a modest amount of additional space for the subband data, independent of image size.


    Debevec, P., and Malik, J. 1997. Recovering High Dynamic Range Radiance Maps from Photographs. In Proceedings of SIGGRAPH 1997.
    Ward Larson, G. 1998. Overcoming Gamut and Dynamic Range Limitations in Digital Images. In Proc. of IS&T/SID 6th Color Imaging Conference.


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