SSPQ - spatial domain perceptual image codec based on subsampling and perceptual quantization. 2012 IEEE International Conference on Image Processing ICIP 2012, 1061 - 1064, IEEE, Lake Buena Vista, Florida, USA, September 2013. [PUMA: JPEG-LS Perceptual coding, distortion, just-noticeable perceptual quantization,] URL