CORRESPONDENCE Statistical-Model Based Methods Separable Markov Random Field Model and Its Applications in Low Level Vision http://dx.doi.org/10.1109/TIP.2012.2208981 ... ......... .. .. ........ ......... ......... ........ ......... ......... ........ ......... ......... ........ ......... ......... J. Sun and M. F. Tappen 402 Restoration and Enhancement Two-Direction Nonlocal Model for Image Denoising http://dx.doi.org/10.1109/TIP.2012.2214043 . ........ X. Zhang, X. Feng, and W. Wang 408 Printing and Halftoning Optimizing the Error Diffusion Filter for Blue Noise Halftoning With Multiscale Error Diffusion http://dx.doi.org/10.1109/TIP.2012.2211370 ....... ......... ......... ........ ..... ..... ......... ........ ......... ..... Y.-H. Fung and Y.-H. Chan 413 www.signalprocessingsociety.org [17] APRIL 2013http://dx.doi.org/10.1109/TIP.2012.2208981 http://dx.doi.org/10.1109/TIP.2012.2214043 http://dx.doi.org/10.1109/TIP.2012.2211370 http://www.signalprocessingsociety.org