imgcodecs(test): rework common I/O test, added grayscale mode

modules/imgcodecs/test/test_common.cpp

@@ -0,0 +1,51 @@
+// 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
+#include "test_precomp.hpp"
+#include "test_common.hpp"
+
+namespace opencv_test {
+
+static
+Mat generateTestImageBGR_()
+{
+    Size sz(640, 480);
+    Mat result(sz, CV_8UC3, Scalar::all(0));
+
+    const string fname = cvtest::findDataFile("../cv/shared/baboon.png");
+    Mat image = imread(fname, IMREAD_COLOR);
+    CV_Assert(!image.empty());
+    CV_CheckEQ(image.size(), Size(512, 512), "");
+    Rect roi((640-512) / 2, 0, 512, 480);
+    image(Rect(0, 0, 512, 480)).copyTo(result(roi));
+    result(Rect(0,  0, 5, 5)).setTo(Scalar(0, 0, 255));  // R
+    result(Rect(5,  0, 5, 5)).setTo(Scalar(0, 255, 0));  // G
+    result(Rect(10, 0, 5, 5)).setTo(Scalar(255, 0, 0));  // B
+    result(Rect(0,  5, 5, 5)).setTo(Scalar(128, 128, 128));  // gray
+    //imshow("test_image", result); waitKey();
+    return result;
+}
+Mat generateTestImageBGR()
+{
+    static Mat image = generateTestImageBGR_();  // initialize once
+    CV_Assert(!image.empty());
+    return image;
+}
+
+static
+Mat generateTestImageGrayscale_()
+{
+    Mat imageBGR = generateTestImageBGR();
+    CV_Assert(!imageBGR.empty());
+
+    Mat result;
+    cvtColor(imageBGR, result, COLOR_BGR2GRAY);
+    return result;
+}
+Mat generateTestImageGrayscale()
+{
+    static Mat image = generateTestImageGrayscale_();  // initialize once
+    return image;
+}
+
+}  // namespace

modules/imgcodecs/test/test_common.hpp

@@ -0,0 +1,15 @@
+// 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
+
+#ifndef OPENCV_TEST_IMGCODECS_COMMON_HPP
+#define OPENCV_TEST_IMGCODECS_COMMON_HPP
+
+namespace opencv_test {
+
+Mat generateTestImageBGR();
+Mat generateTestImageGrayscale();
+
+}  // namespace
+
+#endif  // OPENCV_TEST_IMGCODECS_COMMON_HPP

modules/imgcodecs/test/test_read_write.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 {
 
@@ -145,45 +146,6 @@ TEST(Imgcodecs_Image, read_write_bmp)
 typedef string Ext;
 typedef testing::TestWithParam<Ext> Imgcodecs_Image;
 
-TEST_P(Imgcodecs_Image, read_write)
-{
-    const string ext = this->GetParam();
-    const string full_name = cv::tempfile(ext.c_str());
-    const string _name = TS::ptr()->get_data_path() + "../cv/shared/baboon.png";
-    const double thresDbell = 32;
-
-    Mat image = imread(_name);
-    image.convertTo(image, CV_8UC3);
-    ASSERT_FALSE(image.empty());
-
-    imwrite(full_name, image);
-    Mat loaded = imread(full_name);
-    ASSERT_FALSE(loaded.empty());
-
-    double psnr = cvtest::PSNR(loaded, image);
-    EXPECT_GT(psnr, thresDbell);
-
-    vector<uchar> from_file;
-    FILE *f = fopen(full_name.c_str(), "rb");
-    fseek(f, 0, SEEK_END);
-    long len = ftell(f);
-    from_file.resize((size_t)len);
-    fseek(f, 0, SEEK_SET);
-    from_file.resize(fread(&from_file[0], 1, from_file.size(), f));
-    fclose(f);
-    vector<uchar> buf;
-    imencode("." + ext, image, buf);
-    ASSERT_EQ(buf, from_file);
-
-    Mat buf_loaded = imdecode(Mat(buf), 1);
-    ASSERT_FALSE(buf_loaded.empty());
-
-    psnr = cvtest::PSNR(buf_loaded, image);
-    EXPECT_GT(psnr, thresDbell);
-
-    EXPECT_EQ(0, remove(full_name.c_str()));
-}
-
 const string exts[] = {
 #ifdef HAVE_PNG
     "png",
@@ -209,6 +171,90 @@ const string exts[] = {
 #endif
 };
 
+static
+void test_image_io(const Mat& image, const std::string& fname, const std::string& ext, int imreadFlag, double psnrThreshold)
+{
+    vector<uchar> buf;
+    ASSERT_NO_THROW(imencode("." + ext, image, buf));
+
+    ASSERT_NO_THROW(imwrite(fname, image));
+
+    FILE *f = fopen(fname.c_str(), "rb");
+    fseek(f, 0, SEEK_END);
+    long len = ftell(f);
+    cout << "File size: " << len << " bytes" << endl;
+    EXPECT_GT(len, 1024) << "File is small. Test or implementation is broken";
+    fseek(f, 0, SEEK_SET);
+    vector<uchar> file_buf((size_t)len);
+    EXPECT_EQ(len, (long)fread(&file_buf[0], 1, (size_t)len, f));
+    fclose(f); f = NULL;
+
+    EXPECT_EQ(buf, file_buf) << "imwrite() / imencode() calls must provide the same output (bit-exact)";
+
+    Mat buf_loaded = imdecode(Mat(buf), imreadFlag);
+    EXPECT_FALSE(buf_loaded.empty());
+
+    Mat loaded = imread(fname, imreadFlag);
+    EXPECT_FALSE(loaded.empty());
+
+    EXPECT_EQ(0, cv::norm(loaded, buf_loaded, NORM_INF)) << "imread() and imdecode() calls must provide the same result (bit-exact)";
+
+    double psnr = cvtest::PSNR(loaded, image);
+    EXPECT_GT(psnr, psnrThreshold);
+
+    // not necessary due bitexact check above
+    //double buf_psnr = cvtest::PSNR(buf_loaded, image);
+    //EXPECT_GT(buf_psnr, psnrThreshold);
+
+#if 0  // debug
+    if (psnr <= psnrThreshold /*|| buf_psnr <= thresDbell*/)
+    {
+        cout << "File: " << fname << endl;
+        imshow("origin", image);
+        imshow("imread", loaded);
+        imshow("imdecode", buf_loaded);
+        waitKey();
+    }
+#endif
+}
+
+TEST_P(Imgcodecs_Image, read_write_BGR)
+{
+    const string ext = this->GetParam();
+    const string fname = cv::tempfile(ext.c_str());
+
+    double psnrThreshold = 100;
+    if (ext == "jpg")
+        psnrThreshold = 32;
+
+    Mat image = generateTestImageBGR();
+    EXPECT_NO_THROW(test_image_io(image, fname, ext, IMREAD_COLOR, psnrThreshold));
+
+    EXPECT_EQ(0, remove(fname.c_str()));
+}
+
+TEST_P(Imgcodecs_Image, read_write_GRAYSCALE)
+{
+    const string ext = this->GetParam();
+
+    if (false
+        || ext == "ppm"  // grayscale is not implemented
+        || ext == "ras"  // broken (black result)
+    )
+        throw SkipTestException("GRAYSCALE mode is not supported");
+
+    const string fname = cv::tempfile(ext.c_str());
+
+    double psnrThreshold = 100;
+    if (ext == "jpg")
+        psnrThreshold = 40;
+
+    Mat image = generateTestImageGrayscale();
+    EXPECT_NO_THROW(test_image_io(image, fname, ext, IMREAD_GRAYSCALE, psnrThreshold));
+
+    EXPECT_EQ(0, remove(fname.c_str()));
+}
+
 INSTANTIATE_TEST_CASE_P(imgcodecs, Imgcodecs_Image, testing::ValuesIn(exts));
 
 TEST(Imgcodecs_Image, regression_9376)