Merge pull request #26849 from sturkmen72:apng-writeanimation

APNG encoding optimization #26849

related #26840

### Pull Request Readiness Checklist

See details at https://github.com/opencv/opencv/wiki/How_to_contribute#making-a-good-pull-request

- [x] I agree to contribute to the project under Apache 2 License.
- [x] To the best of my knowledge, the proposed patch is not based on a code under GPL or another license that is incompatible with OpenCV
- [x] The PR is proposed to the proper branch
- [x] There is a reference to the original bug report and related work
- [ ] There is accuracy test, performance test and test data in opencv_extra repository, if applicable
      Patch to opencv_extra has the same branch name.
- [ ] The feature is well documented and sample code can be built with the project CMake

modules/imgcodecs/test/test_animation.cpp

@@ -3,31 +3,10 @@
 // of this distribution and at http://opencv.org/license.html.
 
 #include "test_precomp.hpp"
+#include "test_common.hpp"
 
 namespace opencv_test { namespace {
 
-static void readFileBytes(const std::string& fname, std::vector<unsigned char>& buf)
-{
-    FILE * wfile = fopen(fname.c_str(), "rb");
-    if (wfile != NULL)
-    {
-        fseek(wfile, 0, SEEK_END);
-        size_t wfile_size = ftell(wfile);
-        fseek(wfile, 0, SEEK_SET);
-
-        buf.resize(wfile_size);
-
-        size_t data_size = fread(&buf[0], 1, wfile_size, wfile);
-
-        if(wfile)
-        {
-            fclose(wfile);
-        }
-
-        EXPECT_EQ(data_size, wfile_size);
-    }
-}
-
 static bool fillFrames(Animation& animation, bool hasAlpha, int n = 14)
 {
     // Set the path to the test image directory and filename for loading.

modules/imgcodecs/test/test_common.cpp

@@ -48,4 +48,21 @@ Mat generateTestImageGrayscale()
     return image;
 }
 
+void readFileBytes(const std::string& fname, std::vector<unsigned char>& buf)
+{
+    FILE * wfile = fopen(fname.c_str(), "rb");
+    if (wfile != NULL)
+    {
+        fseek(wfile, 0, SEEK_END);
+        size_t wfile_size = ftell(wfile);
+        fseek(wfile, 0, SEEK_SET);
+
+        buf.resize(wfile_size);
+        size_t data_size = fread(&buf[0], 1, wfile_size, wfile);
+        fclose(wfile);
+
+        EXPECT_EQ(data_size, wfile_size);
+    }
+}
+
 }  // namespace

modules/imgcodecs/test/test_common.hpp

@@ -9,6 +9,7 @@ namespace opencv_test {
 
 Mat generateTestImageBGR();
 Mat generateTestImageGrayscale();
+void readFileBytes(const std::string& fname, std::vector<unsigned char>& buf);
 
 }  // namespace
 

modules/imgcodecs/test/test_png.cpp

@@ -2,6 +2,7 @@
 // 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
 #include "test_precomp.hpp"
+#include "test_common.hpp"
 
 namespace opencv_test { namespace {
 
@@ -327,6 +328,47 @@ const string pngsuite_files_corrupted[] = {
 INSTANTIATE_TEST_CASE_P(/*nothing*/, Imgcodecs_Png_PngSuite_Corrupted,
                         testing::ValuesIn(pngsuite_files_corrupted));
 
+CV_ENUM(PNGStrategy, IMWRITE_PNG_STRATEGY_DEFAULT, IMWRITE_PNG_STRATEGY_FILTERED, IMWRITE_PNG_STRATEGY_HUFFMAN_ONLY, IMWRITE_PNG_STRATEGY_RLE, IMWRITE_PNG_STRATEGY_FIXED);
+CV_ENUM(PNGFilters, IMWRITE_PNG_FILTER_NONE, IMWRITE_PNG_FILTER_SUB, IMWRITE_PNG_FILTER_UP, IMWRITE_PNG_FILTER_AVG, IMWRITE_PNG_FILTER_PAETH, IMWRITE_PNG_FAST_FILTERS, IMWRITE_PNG_ALL_FILTERS);
+
+typedef testing::TestWithParam<testing::tuple<string, PNGStrategy, PNGFilters, int>> Imgcodecs_Png_Encode;
+
+TEST_P(Imgcodecs_Png_Encode, params)
+{
+    const string root = cvtest::TS::ptr()->get_data_path();
+    const string filename = root + "pngsuite/" + get<0>(GetParam());
+
+    const int strategy = get<1>(GetParam());
+    const int filter = get<2>(GetParam());
+    const int compression_level = get<3>(GetParam());
+
+    std::vector<uchar> file_buf;
+    readFileBytes(filename, file_buf);
+    Mat src = imdecode(file_buf, IMREAD_UNCHANGED);
+    EXPECT_FALSE(src.empty()) << "Cannot decode test image " << filename;
+
+    vector<uchar> buf;
+    imencode(".png", src, buf, { IMWRITE_PNG_COMPRESSION, compression_level, IMWRITE_PNG_STRATEGY, strategy, IMWRITE_PNG_FILTER, filter });
+    EXPECT_EQ(buf.size(), file_buf.size());
+}
+
+INSTANTIATE_TEST_CASE_P(/**/,
+    Imgcodecs_Png_Encode,
+    testing::Values(
+        make_tuple("f00n0g08.png", IMWRITE_PNG_STRATEGY_DEFAULT, IMWRITE_PNG_FILTER_NONE, 6),
+        make_tuple("f00n2c08.png", IMWRITE_PNG_STRATEGY_DEFAULT, IMWRITE_PNG_FILTER_NONE, 6),
+        make_tuple("f01n0g08.png", IMWRITE_PNG_STRATEGY_FILTERED, IMWRITE_PNG_FILTER_SUB, 6),
+        make_tuple("f01n2c08.png", IMWRITE_PNG_STRATEGY_FILTERED, IMWRITE_PNG_FILTER_SUB, 6),
+        make_tuple("f02n0g08.png", IMWRITE_PNG_STRATEGY_FILTERED, IMWRITE_PNG_FILTER_UP, 6),
+        make_tuple("f02n2c08.png", IMWRITE_PNG_STRATEGY_FILTERED, IMWRITE_PNG_FILTER_UP, 6),
+        make_tuple("f03n0g08.png", IMWRITE_PNG_STRATEGY_FILTERED, IMWRITE_PNG_FILTER_AVG, 6),
+        make_tuple("f03n2c08.png", IMWRITE_PNG_STRATEGY_FILTERED, IMWRITE_PNG_FILTER_AVG, 6),
+        make_tuple("f04n0g08.png", IMWRITE_PNG_STRATEGY_FILTERED, IMWRITE_PNG_FILTER_PAETH, 6),
+        make_tuple("f04n2c08.png", IMWRITE_PNG_STRATEGY_FILTERED, IMWRITE_PNG_FILTER_PAETH, 6),
+        make_tuple("z03n2c08.png", IMWRITE_PNG_STRATEGY_FILTERED, IMWRITE_PNG_ALL_FILTERS, 3),
+        make_tuple("z06n2c08.png", IMWRITE_PNG_STRATEGY_FILTERED, IMWRITE_PNG_ALL_FILTERS, 6),
+        make_tuple("z09n2c08.png", IMWRITE_PNG_STRATEGY_FILTERED, IMWRITE_PNG_ALL_FILTERS, 9)));
+
 typedef testing::TestWithParam<testing::tuple<string, int, size_t>> Imgcodecs_Png_ImwriteFlags;
 
 TEST_P(Imgcodecs_Png_ImwriteFlags, compression_level)