Image Processing Reference
In-Depth Information
CHAPTER 5
pSQ
Image
quantizer
based
on
contrast
band-pass
filtering
1
Superior School of Mechanical and Electrical Engineers, National Polytechnic
Institute of Mexico, IPN Avenue, Lindavista, Mexico City, Mexico
2
Signal, Image and Communications Department, University of Poitiers, Poitiers, France
Abstract
This work describes pSQ an image quantizer, which employs contrast band-pass filtering and it is based
on Moreno et al. (2014) [
1
]
. In addition, the aim of this work is to explain how to apply perceptual criteria
in order to define a perceptual forward and inverse quantizer. We present its application to the Hi-SET
coder (Moreno and Otazu, 2011) [
2
]. Our approach consists of quantizing wavelet transform coeicients
using some of the human visual system behavior properties. Taking into account that noise is fatal to im-
age compression performance, because it can be both annoying for the observer and consumes excessive
bandwidth when the imagery is transmited. Perceptual quantization reduces unperceivable details and
thus improves both visual impression and transmission properties. The comparison between JPEG2000
coder and the combination of Hi-SET with the proposed perceptual quantizer shows that Hi-SET + pSQ
is not favorable in PSNR than JPEG2000, but the recovered image is more compressed (less bitrate) at
the same or even beter visual quality measured with well-know image quality metrics, such as MSSIM,
UQI, or VIF, for instance.
Keywords
Contrast sensitivity function
Human visual system
JPEG2000
Wavelet transform
Acknowledgment
This work is supported by National Polytechnic Institute of Mexico by means of Project No.
20140096, the Academic Secretary and the Commitee of Operation and Promotion of Academic
Activities (COFAA), National Council of Science and Technology of Mexico by means of Project
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