hopefully fixed test failures and complains from the doc builder

modules/imgproc/src/moments.cpp

@@ -441,13 +441,10 @@ cv::Moments cv::moments( InputArray _src, bool binary )
     int cn = CV_MAT_CN( type );
     Size size = _src.size();
 
-    if( cn > 1 )
-        CV_Error( CV_StsBadArg, "Invalid image type (must be single-channel)" );
-    
     if( size.width <= 0 || size.height <= 0 )
         return m;
 
-    if( ocl::useOpenCL() && depth == CV_8U && !binary &&
+    if( ocl::useOpenCL() && type == CV_8UC1 && !binary &&
         _src.isUMat() && ocl_moments(_src, m) )
         ;
     else
@@ -456,6 +453,9 @@ cv::Moments cv::moments( InputArray _src, bool binary )
         if( mat.checkVector(2) >= 0 && (depth == CV_32F || depth == CV_32S))
             return contourMoments(mat);
 
+        if( cn > 1 )
+            CV_Error( CV_StsBadArg, "Invalid image type (must be single-channel)" );
+
         if( binary || depth == CV_8U )
             func = momentsInTile<uchar, int, int>;
         else if( depth == CV_16U )