Change blend default to 50%

Former-commit-id: 9acc8de1aee1ff8adfcaa8a1b74fdca79b49a6bb
Former-commit-id: 30c212d20452f968a8d1794957fdcbde3515c9ff
Former-commit-id: eaec6b115d3fcfe045fabe5dad097352620e9884

src/ImageProcessor/Filters/ImageFilterExtensions.cs

@@ -42,7 +42,7 @@ namespace ImageProcessor.Filters
         /// <param name="image">The image to blend with the currently processing image.</param>
         /// <param name="percent">The opacity of the image image to blend. Must be between 0 and 100.</param>
         /// <returns>The <see cref="Image"/>.</returns>
-        public static Image Blend(this Image source, ImageBase image, int percent = 100)
+        public static Image Blend(this Image source, ImageBase image, int percent = 50)
         {
             return source.Process(source.Bounds, new Blend(image, percent));
         }