pSQ: Image quantizer based on contrast band-pass filtering

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 coefficients using some of the human visual system behavior properties. Taking into account that noise is fatal to image compression performance, because it can be both annoying for the observer and consumes excessive bandwidth when the imagery is transmitted. 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 better visual quality measured with well-know image quality metrics, such as MSSIM, UQI, or VIF, for instance.