Contrast Sensitivity of the Wavelet, Dual Tree Complex Wavelet, Curvelet, and Steerable Pyramid Transforms

P.R. Hill

University of Bristol

A. Achim

University of Bristol

M.E. Al-Mualla

KUSTAR

D.R. Bull

University of Bristol

About

This project is concerned with the application of machine learning techniques to develop a state-of-the-art detection and prediction system for spatiotemporal events found within remote sensing data; specifically, Harmful Algal Bloom events (HABs).

Funders
EPSRC: the Vision for the Future Platform Grant: EP/M000885/1
VSAP–Khalifa University of Science, Technology and Research
Collaborators
Kustar/ MASDAR, UAE, NASA

Abstract

Accurate estimation of the contrast sensitivity of the human visual system is crucial for perceptually based image processing in applications such as compression, fusion and denoising. Conventional contrast sensitivity functions (CSFs) have been obtained using fixed-sized Gabor functions. However, the basis functions of multiresolution decompositions such as wavelets often resemble Gabor functions but are of variable size and shape. Therefore to use the conventional CSFs in such cases is not appropriate. We have therefore conducted a set of psychophysical tests in order to obtain the CSF for a range of multiresolution transforms: the discrete wavelet transform, the steerable pyramid, the dual-tree complex wavelet transform, and the curvelet transform. These measures were obtained using contrast variation of each transforms’ basis functions in a 2AFC experiment combined with an adapted version of the QUEST psychometric function method. The results enable future image processing applications that exploit these transforms such as signal fusion, superresolution processing, denoising and motion estimation, to be perceptually optimized in a principled fashion. The results are compared with an existing vision model (HDR-VDP2) and are used to show quantitative improvements within a denoising application compared with using conventional CSF values.

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Citation

@article{hill2016contrast,
  title={Contrast sensitivity of the wavelet, dual tree complex wavelet, curvelet, and steerable pyramid transforms},
  author={Hill, Paul and Achim, Alin and Al-Mualla, Mohammed E and Bull, David},
  journal={IEEE Transactions on Image Processing},
  volume={25},
  number={6},
  pages={2739--2751},
  year={2016},
  publisher={IEEE}
}