32bit rgb bmp file should not copy data as rgba

modules/imgcodecs/src/grfmt_bmp.cpp

@@ -180,7 +180,7 @@ bool  BmpDecoder::readHeader()
         throw;
     }
     // in 32 bit case alpha channel is used - so require CV_8UC4 type
-    m_type = iscolor ? (m_bpp == 32 ? CV_8UC4 : CV_8UC3 ) : CV_8UC1;
+    m_type = iscolor ? ((m_bpp == 32 && m_rle_code != BMP_RGB) ? CV_8UC4 : CV_8UC3 ) : CV_8UC1;
     m_origin = m_height > 0 ? IPL_ORIGIN_BL : IPL_ORIGIN_TL;
     m_height = std::abs(m_height);
 

modules/imgcodecs/test/test_grfmt.cpp

@@ -280,6 +280,16 @@ TEST(Imgcodecs_Bmp, read_rle8)
     EXPECT_PRED_FORMAT2(cvtest::MatComparator(0, 0), rle, ord);
 }
 
+TEST(Imgcodecs_Bmp, read_32bit_rgb)
+{
+    const string root = cvtest::TS::ptr()->get_data_path();
+    const string filenameInput = root + "readwrite/test_32bit_rgb.bmp";
+
+    const Mat img = cv::imread(filenameInput, IMREAD_UNCHANGED);
+    ASSERT_FALSE(img.empty());
+    ASSERT_EQ(CV_8UC3, img.type());
+}
+
 #ifdef HAVE_IMGCODEC_HDR
 TEST(Imgcodecs_Hdr, regression)
 {