Merge pull request #27087 from sturkmen72:apng_CV_16U

asmorkalov · web-flow · commit 41e3fcc73eea · 2025-03-20T17:29:45.000+03:00
Fixing imread() function 16 bit APNG reading problem
diff --git a/modules/imgcodecs/src/grfmt_png.cpp b/modules/imgcodecs/src/grfmt_png.cpp
@@ -451,6 +451,9 @@ bool  PngDecoder::readData( Mat& img )
                         delay_den = 100;
                     m_animation.durations.push_back(cvRound(1000.*delay_num/delay_den));
 
+                    if (mat_cur.depth() == CV_16U && img.depth() == CV_8U)
+                        mat_cur.convertTo(mat_cur, CV_8U, 1. / 255);
+
                     if (mat_cur.channels() == img.channels())
                         mat_cur.copyTo(img);
                     else if (img.channels() == 1)
@@ -485,7 +488,7 @@ bool  PngDecoder::readData( Mat& img )
                     return false;
                 }
                 // Asking for blend over with no alpha is invalid.
-                if (bop == 1 && img.channels() != 4)
+                if (bop == 1 && mat_cur.channels() != 4)
                 {
                     return false;
                 }
@@ -514,6 +517,9 @@ bool  PngDecoder::readData( Mat& img )
                         delay_den = 100;
                     m_animation.durations.push_back(cvRound(1000.*delay_num/delay_den));
 
+                    if (mat_cur.depth() == CV_16U && img.depth() == CV_8U)
+                        mat_cur.convertTo(mat_cur, CV_8U, 1. / 255);
+
                     if (mat_cur.channels() == img.channels())
                         mat_cur.copyTo(img);
                     else if (img.channels() == 1)
@@ -775,6 +781,9 @@ bool PngDecoder::processing_start(void* frame_ptr, const Mat& img)
     else
         png_set_rgb_to_gray(m_png_ptr, 1, 0.299, 0.587); // RGB->Gray
 
+    if (!isBigEndian() && m_bit_depth == 16)
+        png_set_swap(m_png_ptr);
+
     for (size_t i = 0; i < m_chunksInfo.size(); i++)
         png_process_data(m_png_ptr, m_info_ptr, m_chunksInfo[i].p.data(), m_chunksInfo[i].p.size());
 
diff --git a/modules/imgcodecs/src/loadsave.cpp b/modules/imgcodecs/src/loadsave.cpp
@@ -505,7 +505,7 @@ imread_( const String& filename, int flags, OutputArray mat )
     {
         if (decoder->readData(real_mat))
         {
-            CV_CheckTrue(original_ptr == real_mat.data, "Internal imread issue");
+            CV_CheckTrue((decoder->getFrameCount() > 1) || original_ptr == real_mat.data, "Internal imread issue");
             success = true;
         }
     }
diff --git a/modules/imgcodecs/test/test_animation.cpp b/modules/imgcodecs/test/test_animation.cpp
@@ -626,7 +626,7 @@ TEST(Imgcodecs_APNG, imencode_animation)
     EXPECT_TRUE(imencodeanimation(".png", gt_animation, buf));
     EXPECT_TRUE(imdecodeanimation(buf, mem_animation));
 
-        EXPECT_EQ(mem_animation.frames.size(), gt_animation.frames.size());
+    EXPECT_EQ(mem_animation.frames.size(), gt_animation.frames.size());
     EXPECT_EQ(mem_animation.bgcolor, gt_animation.bgcolor);
     EXPECT_EQ(mem_animation.loop_count, gt_animation.loop_count);
     for (size_t i = 0; i < gt_animation.frames.size(); i++)
@@ -638,4 +638,61 @@ TEST(Imgcodecs_APNG, imencode_animation)
 
 #endif // HAVE_PNG
 
+#if defined(HAVE_PNG) || defined(HAVE_SPNG)
+
+TEST(Imgcodecs_APNG, imread_animation_16u)
+{
+    // Set the path to the test image directory and filename for loading.
+    const string root = cvtest::TS::ptr()->get_data_path();
+    const string filename = root + "readwrite/033.png";
+
+    Mat img = imread(filename, IMREAD_UNCHANGED);
+    ASSERT_FALSE(img.empty());
+    EXPECT_TRUE(img.type() == CV_16UC4);
+    EXPECT_EQ(0,     img.at<ushort>(0, 0));
+    EXPECT_EQ(0,     img.at<ushort>(0, 1));
+    EXPECT_EQ(65280, img.at<ushort>(0, 2));
+    EXPECT_EQ(65535, img.at<ushort>(0, 3));
+
+    img = imread(filename, IMREAD_GRAYSCALE);
+    ASSERT_FALSE(img.empty());
+    EXPECT_TRUE(img.type() == CV_8UC1);
+    EXPECT_EQ(76, img.at<uchar>(0, 0));
+
+    img = imread(filename, IMREAD_COLOR);
+    ASSERT_FALSE(img.empty());
+    EXPECT_TRUE(img.type() == CV_8UC3);
+    EXPECT_EQ(0,   img.at<uchar>(0, 0));
+    EXPECT_EQ(0,   img.at<uchar>(0, 1));
+    EXPECT_EQ(255, img.at<uchar>(0, 2));
+
+    img = imread(filename, IMREAD_COLOR_RGB);
+    ASSERT_FALSE(img.empty());
+    EXPECT_TRUE(img.type() == CV_8UC3);
+    EXPECT_EQ(255, img.at<uchar>(0, 0));
+    EXPECT_EQ(0,   img.at<uchar>(0, 1));
+    EXPECT_EQ(0,   img.at<uchar>(0, 2));
+
+    img = imread(filename, IMREAD_ANYDEPTH);
+    ASSERT_FALSE(img.empty());
+    EXPECT_TRUE(img.type() == CV_16UC1);
+    EXPECT_EQ(19519, img.at<ushort>(0, 0));
+
+    img = imread(filename, IMREAD_COLOR | IMREAD_ANYDEPTH);
+    ASSERT_FALSE(img.empty());
+    EXPECT_TRUE(img.type() == CV_16UC3);
+    EXPECT_EQ(0,     img.at<ushort>(0, 0));
+    EXPECT_EQ(0,     img.at<ushort>(0, 1));
+    EXPECT_EQ(65280, img.at<ushort>(0, 2));
+
+    img = imread(filename, IMREAD_COLOR_RGB | IMREAD_ANYDEPTH);
+    ASSERT_FALSE(img.empty());
+    EXPECT_TRUE(img.type() == CV_16UC3);
+    EXPECT_EQ(65280, img.at<ushort>(0, 0));
+    EXPECT_EQ(0,     img.at<ushort>(0, 1));
+    EXPECT_EQ(0,     img.at<ushort>(0, 2));
+}
+
+#endif // HAVE_PNG || HAVE_SPNG
+
 }} // namespace

Original file line number	Diff line number	Diff line change
`@@ -505,7 +505,7 @@ imread_( const String& filename, int flags, OutputArray mat )`
`505`	`505`	`{`
`506`	`506`	`if (decoder->readData(real_mat))`
`507`	`507`	`{`
`508`		`- CV_CheckTrue(original_ptr == real_mat.data, "Internal imread issue");`
	`508`	`+ CV_CheckTrue((decoder->getFrameCount() > 1) \|\| original_ptr == real_mat.data, "Internal imread issue");`
`509`	`509`	`success = true;`
`510`	`510`	`}`
`511`	`511`	`}`