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Proceedings Paper

Spatial adaptive upsampling filter for HDR image based on multiple luminance range
Author(s): Qian Chen; Guan-ming Su; Yin Peng
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Paper Abstract

In this paper, we propose an adaptive upsampling filter to spatially upscale HDR image based on luminance range of the HDR picture in each color channel. It first searches for the optimal luminance range values to partition an HDR image to three different parts: dark, mid-tone and highlight. Then we derive the optimal set of filter coefficients both vertically and horizontally for each part. When the HDR pixel is within the dark area, we apply one set of filter coefficients to vertically upsample the pixel. If the HDR pixel falls in mid-tone area, we apply another set of filter for vertical upsampling. Otherwise the HDR pixel is in highlight area, another set of filter will be applied for vertical upsampling. Horizontal upsampling will be carried out likewise based on its luminance. The inherent idea to partition HDR image to different luminance areas is based on the fact that most HDR images are created from multiple exposures. Different exposures usually demonstrate slight variation in captured signal statistics, such as noise level, subtle misalignment etc. Hence, to group different regions to three luminance partitions actually helps to eliminate the variation between signals, and to derive optimal filter for each group with signals of lesser variation is certainly more efficient than for the entire HDR image. Experimental results show that the proposed adaptive upsampling filter based on luminance ranges outperforms the optimal upsampling filter around 0.57dB for R channel, 0.44dB for G channel and 0.31dB for B channel.

Paper Details

Date Published: 7 March 2014
PDF: 10 pages
Proc. SPIE 9023, Digital Photography X, 902311 (7 March 2014); doi: 10.1117/12.2042267
Show Author Affiliations
Qian Chen, Dolby Labs., Inc. (United States)
Guan-ming Su, Dolby Labs., Inc. (United States)
Yin Peng, Dolby Labs., Inc. (United States)

Published in SPIE Proceedings Vol. 9023:
Digital Photography X
Nitin Sampat; Radka Tezaur; Sebastiano Battiato; Boyd A. Fowler, Editor(s)

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