dnn: handle 4-channel images in blobFromImage (#9944)

modules/dnn/test/test_misc.cpp

@@ -0,0 +1,30 @@
+// This file is part of OpenCV project.
+// It is subject to the license terms in the LICENSE file found in the top-level directory
+// of this distribution and at http://opencv.org/license.html.
+//
+// Copyright (C) 2017, Intel Corporation, all rights reserved.
+// Third party copyrights are property of their respective owners.
+
+#include "test_precomp.hpp"
+
+namespace cvtest
+{
+
+TEST(blobFromImage_4ch, Regression)
+{
+    Mat ch[4];
+    for(int i = 0; i < 4; i++)
+        ch[i] = Mat::ones(10, 10, CV_8U)*i;
+
+    Mat img;
+    merge(ch, 4, img);
+    Mat blob = dnn::blobFromImage(img, 1., Size(), Scalar(), false, false);
+
+    for(int i = 0; i < 4; i++)
+    {
+        ch[i] = Mat(img.rows, img.cols, CV_32F, blob.ptr(0, i));
+        ASSERT_DOUBLE_EQ(cvtest::norm(ch[i], cv::NORM_INF), i);
+    }
+}
+
+}