論文

査読有り 責任著者
2020年12月

Variable macropixel spectral-spatial transforms with intra- and inter-color decorrelations for arbitrary RGB CFA-sampled raw images

IEEE Signal Processing Letters
  • Suzuki, Taizo
  • ,
  • Kyochi, Seisuke

27
1
開始ページ
466
終了ページ
470
記述言語
英語
掲載種別
研究論文(学術雑誌)
DOI
10.1109/LSP.2020.2977500
出版者・発行元
IEEE

A raw image captured by a color filter array (CFA), such as a Bayer pattern, is usually compressed after demosaicing with some processings (denoising, deblurring, tone-mapping, and so on). However, since photographers, designers, and high-end users prefer to work with the raw image sampled by CFA (referred to as "raw image") directly, a raw image should be compressed before demosaicing. For effective raw image compression, this study introduces variable macropixel spectral-spatial transforms (VMSSTs), that can successfully decorrelate not only Bayer raw images but any other pure-color (RGB) ones. The proposed VMSSTs are designed by the following two steps: 1) intra-color decorrelation and 2) inter-color decorrelation. In lossless compression with JPEG 2000, compared with methods which do not use transforms, the VMSSTs reduced the average bitrates of three types of CFAs: from approximately 0.09 to 0.12 bpp for the modified Bayer CFA, from 0.25 to 0.65 bpp for the diagonal stripe CFA, and from 0.33 to 0.70 bpp for the Fujifilm X-Trans CFA due to their high color decorrelation efficiency. In addition, in lossy compression with JPEG 2000, compared with a rearranged method, the VMSSTs improved the average bitrates of the Bjontegaard delta by around 3.97%, 14.95%, and 18.65% for each CFA model, respectively. Although a data-dependent adaptive transformation, the Karhunen-Loeve transform (KLT), showed the best performance in lossy compression, the introduced VMSSTs have shown performances comparable to those of the KLT in lossless compression, despite their simple structures.

リンク情報
DOI
https://doi.org/10.1109/LSP.2020.2977500
ID情報
  • DOI : 10.1109/LSP.2020.2977500
  • ISSN : 1070-9908

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