Added samplingFactor to the Image class of Magick++ (#3711).

Magick++/lib/Image.cpp

@@ -1352,6 +1352,17 @@ size_t Magick::Image::rows(void) const
   return(constImage()->rows);
 }
 
+void Magick::Image::samplingFactor(const std::string &samplingFactor_)
+{
+  modifyImage();
+  options()->samplingFactor(samplingFactor_);
+}
+
+std::string Magick::Image::samplingFactor(void) const
+{
+  return(constOptions()->samplingFactor());
+}
+
 void Magick::Image::scene(const size_t scene_)
 {
   modifyImage();

Magick++/lib/Magick++/Image.h

@@ -397,6 +397,10 @@ namespace Magick
     // The number of pixel rows in the image
     size_t rows(void) const;
 
+    // Image sampling factor
+    void samplingFactor(const std::string &samplingFactor_);
+    std::string samplingFactor(void) const;
+
     // Image scene number
     void scene(const size_t scene_);
     size_t scene(void) const;