Nonsubsampled contourlet transform based tone‐mapping operator to optimize the dynamic range of diatom shells. Issue 9 (29th March 2021)

• Record Type: Journal Article
• Authors: Singh, Harbinder; Cristobal, Gabriel; Blanco, Saul; Bueno, Gloria; Sanchez, Carlos
• Is Part Of: Microscopy research and technique. Volume 84:Issue 9(2021)
• Page Start: 2034
• Page End: 2045
• Publication Date: 2021-03-29
• Subjects: diatom -- HDR -- microscopy -- multi‐exposure -- tone mapping; Electron microscopy -- Technique -- Periodicals; Microscopy -- Periodicals; Microscopy -- Technique -- Periodicals; 502.825
• DOI: 10.1002/jemt.23759
• Languages: English
• ISSNs: 1059-910X

Abstract

Abstract: The diatoms have intricate silica‐based cell walls with multi‐scale patterns. High dynamic range (HDR) imaging is widely used to examine the three‐dimensional structure of diatoms for recovering the wide range of contrast and brightness. In order to construct a HDR image of a diatom, multiple images of the specimen are taken at different exposure settings with bright or dark field microscopy. In the proposed method, multi‐scale decomposition based on nonsubsampled contourlet transform is adopted to separate the structured and detailed information of the HDR image. And then, by processing all layers independently, the tone‐mapped image is reconstructed to retain details present in the dark and light regions. Quantitative and qualitative analysis is performed in order to assess the performance of the proposed and seven existing tone‐mapping operators. In analysis, the study indicates that the proposed method enhances the diatom frustules to extract more details. Abstract : Architecture of proposed nonsubsampled contourlet transform (NSCT) based tone‐mapping (NT‐TM) approach. Input high dynamic range image ( I ) is converted to log‐luminance channel ( L ). The analysis filter bank is used in NSCT domain for multi‐scale decomposition. After dynamic range compression, synthesis filter bank is used for reconstruction in NSCT domain. Tone‐mapping approach is proposed for high dynamic range (HDR) microscopy images of diatom species The approach is based on nonsubsampled contourlet transform based multi‐scale decomposition The lowpass and directional high frequency subbands of HDR images are processed separately for preserving details present in the dark and bright regions The fine structures and contours of diatom frustules are enhanced that can be used for identification and classification of different species.