From: cristy <urban-warrior@git.imagemagick.org>
Date: Sun, 5 Sep 2010 01:37:25 +0000 (+0000)
Subject: (no commit message)
X-Git-Tag: 7.0.1-0~8977
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=21ce88aa18df166215a870b34a823dd7c025615e;p=imagemagick

---

diff --git a/magick/resize.c b/magick/resize.c
index 221981027..551cc7dbc 100644
--- a/magick/resize.c
+++ b/magick/resize.c
@@ -149,9 +149,13 @@ static MagickRealType Blackman(const MagickRealType x,
   const ResizeFilter *magick_unused(resize_filter))
 {
   /*
-    Blackman: 2rd Order cosine windowing function.
+    Blackman: 2rd Order cosine windowing function:
+      0.42 + 0.5 cos(pi x) + 0.08 cos(2pi x)
+      Refactored by Chantal Racette and Nicolas Robidoux so it needs
+      only one trig call and five flops.
   */
-  return(0.42+0.5*cos(MagickPI*(double) x)+0.08*cos(2.0*MagickPI*(double) x));
+  const double alpha = cos(MagickPI*(double) x);
+  return(0.34+alpha*(0.5+alpha*0.16));
 }
 
 static MagickRealType Bohman(const MagickRealType x,