Doc clarifications for Fl_Image methods:

> inactive()
	> desaturate()
	> color_average()



git-svn-id: file:///fltk/svn/fltk/branches/branch-1.3@10725 ea41ed52-d2ee-0310-a9c1-e6b18d33e121

FL/Fl_Image.H

@@ -140,8 +140,10 @@ class FL_EXPORT Fl_Image {
   /**
     The inactive() method calls
     color_average(FL_BACKGROUND_COLOR, 0.33f) to produce 
-    an image that appears grayed out. <I>This method does not 
+    an image that appears grayed out.
-    alter the original image data.</I>
+
+    An internal copy is made of the original image before
+    changes are applied, to avoid modifying the original image.
   */
   void inactive() { color_average(FL_GRAY, .33f); }
   virtual void desaturate();

src/Fl_Image.cxx

@@ -87,8 +87,10 @@ Fl_Image *Fl_Image::copy(int W, int H) {
   argument specifies the amount of the original image to combine
   with the color, so a value of 1.0 results in no color blend, and
   a value of 0.0 results in a constant image of the specified
-  color. <I>The original image data is not altered by this
+  color. 
-  method.</I>
+
+  An internal copy is made of the original image before
+  changes are applied, to avoid modifying the original image.
 */
 void Fl_Image::color_average(Fl_Color, float) {
 }
@@ -96,8 +98,10 @@ void Fl_Image::color_average(Fl_Color, float) {
 /**
   The desaturate() method converts an image to
   grayscale. If the image contains an alpha channel (depth = 4),
-  the alpha channel is preserved. <I>This method does not alter
+  the alpha channel is preserved.
-  the original image data.</I>
+  
+  An internal copy is made of the original image before
+  changes are applied, to avoid modifying the original image.
 */
 void Fl_Image::desaturate() {
 }