EWA LanczosSharp is a really good low pass filter. Not as sharp as orthogonal Lanczos, but "cleaner".
Unlike what I did with orthogonal Lanczos, I will use a possibly slightly "unsafe" contrast value, namely the one that gives an enlarged black square that stays within 2.3 JND of black, when the square is on a white background. With LanczosSharp, the corresponding contrast value is about 12.09375. (Maybe this value is slightly on the high side? This method is too new for me to know for sure.)
Code: Select all
magick INPUT.IMG -colorspace RGB +sigmoidal-contrast 12.09375 -filter Lanczossharp -distort Resize 400% -sigmoidal-contrast 12.09375 -colorspace sRGB OUTPUT.IMG
First, I'll repeat the four comparative tests based on http://www.wisdom.weizmann.ac.il/~vision/SingleImageSR.html. (Note that I have absolutely nothing to do with this site or the methods tested therein.) I'll also add an enlargement of text which I put together myself (with GIMP).