From: anthony <anthony@git.imagemagick.org>
Date: Tue, 14 Sep 2010 08:56:31 +0000 (+0000)
Subject: Proper fix of the box filter
X-Git-Tag: 7.0.1-0~8930
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=1f90a6ba514c936aa42abf2c92f041199bcf05a0;p=imagemagick

Proper fix of the box filter
---

diff --git a/magick/resize.c b/magick/resize.c
index e1f1de248..745ad785f 100644
--- a/magick/resize.c
+++ b/magick/resize.c
@@ -176,12 +176,12 @@ static MagickRealType Bohman(const MagickRealType x,
 }
 
 static MagickRealType Box(const MagickRealType x,
-  const ResizeFilter *magick_unused(resize_filter))
+  const ResizeFilter *resize_filter)
 {
   /*
-    Just return 1.0; the filter will be clipped by its support window.
+    Return a Box fillter up to its support size.
   */
-  if ( x < 0.5 )
+  if ( x < resize_filter->support )
     return(1.0);
   return(0.0);
 }
@@ -770,7 +770,7 @@ MagickExport ResizeFilter *AcquireResizeFilter(const Image *image,
   {
     MagickRealType
       (*function)(const MagickRealType, const ResizeFilter*),
-      support,  /* default support size for function as a filter */
+      support,  /* default support size for function as a weighting filter */
       scale,    /* windowing function range, for scaling windowing function */
       B,C;      /* Cubic Filter factors for a CubicBC function, else ignored */
   } const filters[SentinelFilter] =
@@ -966,8 +966,8 @@ MagickExport ResizeFilter *AcquireResizeFilter(const Image *image,
   if (artifact != (const char *) NULL)
     resize_filter->window_support=fabs(StringToDouble(artifact));
   /*
-    Adjust window function X scaling to fit
-    Avoids a division on every filter call.
+    Adjust window function scaling to the windowing support for
+    weighting function.  This avoids a division on every filter call.
   */
   resize_filter->scale /= resize_filter->window_support;
   /*