From: nicolas Date: Sun, 14 Nov 2010 17:23:29 +0000 (+0000) Subject: (no commit message) X-Git-Tag: 7.0.1-0~8508 X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=fc61294fcd25e32180cbd2cb24eeb5801c1ae087;p=imagemagick --- diff --git a/magick/resize.c b/magick/resize.c index fbda1fc43..4451caefb 100644 --- a/magick/resize.c +++ b/magick/resize.c @@ -532,14 +532,14 @@ static MagickRealType Welsh(const MagickRealType x, % and rational (high Q) approximations, and will be used by default in % most cases. % -% Lanczos filter is a special 3-lobed Sinc-windowed Sinc filter -% (promoted to Jinc-windowed Jinc for cylindrical use). This is the -% most popular windowed filter. -% -% LanczosSharp is a slightly sharpened (blur=0.9812505644269356) form -% of the Lanczos filter. It was designed specifically for -% cylindrical EWA (Elliptical Weighted Average) distortion (as a -% Jinc-Jinc filter); it can also be used as a slightly sharper +% The Lanczos filter is a special 3-lobed Sinc-windowed Sinc filter +% (promoted to Jinc-windowed Jinc for cylindrical (Elliptical +% Weighted Average) use). The Sinc version is the most popular +% windowed filter. +% +% LanczosSharp is a slightly sharpened (blur=0.9812505644269356 < 1) +% form of the Lanczos filter, specifcally designed for EWA distortion +% (as a Jinc-Jinc); it can also be used as a slightly sharper % orthogonal Lanczos (Sinc-Sinc) filter. The chosen blur value comes % as close as possible to satisfying the following condition without % changing the character of the corresponding EWA filter: @@ -552,7 +552,8 @@ static MagickRealType Welsh(const MagickRealType x, % Lanczos filters. The 'sharp' version uses a blur factor of % 0.958027803631219, again chosen because the resulting EWA filter % comes as close as possible to satisfying the above -% condition. (Comment from Nicolas: this value may change slightly.) +% condition. (Comment from Nicolas: value may change following the +% use of a better optimization technique.) % % Robidoux is another filter tuned for EWA. It is the Keys cubic % filter defined by B=(228 - 108 sqrt(2))/199. Robidoux satisfies the