From 14ef67ad835cab0e86751dcd03dd61d740b8550f Mon Sep 17 00:00:00 2001
From: Dirk Lemstra <dirk@git.imagemagick.org>
Date: Thu, 26 Apr 2018 11:17:28 +0000
Subject: [PATCH] Added support for channel traits to LocalContrastImage.

---
 Magick++/lib/Image.cpp        | 14 ++++++++++++++
 Magick++/lib/Magick++/Image.h |  2 ++
 MagickCore/effect.c           | 21 +++++++++++++++------
 3 files changed, 31 insertions(+), 6 deletions(-)

diff --git a/Magick++/lib/Image.cpp b/Magick++/lib/Image.cpp
index af953aedc..ec1688490 100644
--- a/Magick++/lib/Image.cpp
+++ b/Magick++/lib/Image.cpp
@@ -3527,6 +3527,20 @@ void Magick::Image::localContrast(const double radius_,const double strength_)
   ThrowImageException;
 }
 
+void Magick::Image::localContrastChannel(const ChannelType channel_,
+  const double radius_,const double strength_)
+{
+  MagickCore::Image
+    *newImage;
+
+  GetPPException;
+  GetAndSetPPChannelMask(channel_);
+  newImage=LocalContrastImage(constImage(),radius_,strength_,exceptionInfo);
+  RestorePPChannelMask;
+  replaceImage(newImage);
+  ThrowImageException;
+}
+
 void Magick::Image::magnify(void)
 {
   MagickCore::Image
diff --git a/Magick++/lib/Magick++/Image.h b/Magick++/lib/Magick++/Image.h
index e16c1755b..33df63f3e 100644
--- a/Magick++/lib/Magick++/Image.h
+++ b/Magick++/lib/Magick++/Image.h
@@ -1065,6 +1065,8 @@ namespace Magick
 
     // Local contrast enhancement
     void localContrast(const double radius_,const double strength_);
+    void localContrastChannel(const ChannelType channel_,const double radius_,
+      const double strength_);
 
     // Magnify image by integral size
     void magnify(void);
diff --git a/MagickCore/effect.c b/MagickCore/effect.c
index 7fb5172f3..ca20e6d8b 100644
--- a/MagickCore/effect.c
+++ b/MagickCore/effect.c
@@ -1889,6 +1889,9 @@ MagickExport Image *LocalContrastImage(const Image *image,const double radius,
           sum,
           weight;
 
+        PixelTrait
+          traits;
+
         weight=1.0f;
         sum=0;
         pix=pixels+x;
@@ -1906,12 +1909,18 @@ MagickExport Image *LocalContrastImage(const Image *image,const double radius,
         srcVal=(float) GetPixelLuma(image,p);
         mult=(srcVal-(sum/totalWeight))*(strength/100.0f);
         mult=(srcVal+mult)/srcVal;
-        SetPixelRed(contrast_image,ClampToQuantum(GetPixelRed(image,p)*mult),
-          q);
-        SetPixelGreen(contrast_image,ClampToQuantum(GetPixelGreen(image,p)*
-          mult),q);
-        SetPixelBlue(contrast_image,ClampToQuantum(GetPixelBlue(image,p)*mult),
-          q);
+        traits=GetPixelChannelTraits(image,RedPixelChannel);
+        if ((traits & UpdatePixelTrait) != 0)
+          SetPixelRed(contrast_image,ClampToQuantum(GetPixelRed(image,p)*mult),
+            q);
+        traits=GetPixelChannelTraits(image,GreenPixelChannel);
+        if ((traits & UpdatePixelTrait) != 0)
+          SetPixelGreen(contrast_image,ClampToQuantum(GetPixelGreen(image,p)*
+            mult),q);
+        traits=GetPixelChannelTraits(image,BluePixelChannel);
+        if ((traits & UpdatePixelTrait) != 0)
+          SetPixelBlue(contrast_image,ClampToQuantum(GetPixelBlue(image,p)*
+            mult),q);
         p+=image->number_channels;
         q+=contrast_image->number_channels;
       }
-- 
2.40.0