From 2238ac7d596fa94013eaeb5a1797753b141231ea Mon Sep 17 00:00:00 2001
From: xiongzhen <xiongzh@mail2.sysu.edu.cn>
Date: Fri, 13 May 2022 09:44:25 +0300
Subject: [PATCH] Apply TIFFTAG_PREDICTOR option for LZW, DEFLATE and
 ADOBE_DEFLATE compression cases for smaller files.

---
 modules/imgcodecs/src/grfmt_tiff.cpp |  2 +-
 modules/imgcodecs/test/test_tiff.cpp | 42 ++++++++++++++++++++++++++++
 2 files changed, 43 insertions(+), 1 deletion(-)

diff --git a/modules/imgcodecs/src/grfmt_tiff.cpp b/modules/imgcodecs/src/grfmt_tiff.cpp
index d6f05f7a65..04df6ff8bb 100644
--- a/modules/imgcodecs/src/grfmt_tiff.cpp
+++ b/modules/imgcodecs/src/grfmt_tiff.cpp
@@ -901,7 +901,7 @@ bool TiffEncoder::writeLibTiff( const std::vector<Mat>& img_vec, const std::vect
 
         CV_TIFF_CHECK_CALL(TIFFSetField(tif, TIFFTAG_SAMPLEFORMAT, depth >= CV_32F ? SAMPLEFORMAT_IEEEFP : SAMPLEFORMAT_UINT));
 
-        if (page_compression != COMPRESSION_NONE)
+        if (page_compression == COMPRESSION_LZW || page_compression == COMPRESSION_ADOBE_DEFLATE || page_compression == COMPRESSION_DEFLATE)
         {
             CV_TIFF_CHECK_CALL(TIFFSetField(tif, TIFFTAG_PREDICTOR, predictor));
         }
diff --git a/modules/imgcodecs/test/test_tiff.cpp b/modules/imgcodecs/test/test_tiff.cpp
index add15ff681..063bd9ae50 100644
--- a/modules/imgcodecs/test/test_tiff.cpp
+++ b/modules/imgcodecs/test/test_tiff.cpp
@@ -219,6 +219,48 @@ TEST(Imgcodecs_Tiff, readWrite_32FC3_RAW)
     EXPECT_EQ(0, remove(filenameOutput.c_str()));
 }
 
+TEST(Imgcodecs_Tiff, readWrite_predictor)
+{
+    /* see issue #21871
+     */
+    const uchar sample_data[160] = {
+        0xff, 0xff, 0xff, 0xff, 0x88, 0x88, 0xff, 0xff, 0x88, 0x88, 0xff, 0xff, 0xff, 0xff, 0xff, 0x88,
+        0xff, 0xff, 0x00, 0x00, 0x00, 0x00, 0x00, 0xff, 0x00, 0x00, 0xff, 0xff, 0xff, 0xff, 0x00, 0x00,
+        0xff, 0x00, 0x00, 0x44, 0xff, 0xff, 0x88, 0xff, 0x33, 0x00, 0x66, 0xff, 0xff, 0x88, 0x00, 0x44,
+        0x88, 0x00, 0x44, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x00, 0x44, 0xff, 0xff, 0x11, 0x00, 0xff,
+        0x11, 0x00, 0x88, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x00, 0x00, 0xff, 0xff, 0x00, 0x00, 0xff,
+        0x11, 0x00, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x33, 0x00, 0x88, 0xff, 0x00, 0x66, 0xff,
+        0x11, 0x00, 0x66, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x00, 0x44, 0x33, 0x00, 0xff, 0xff,
+        0x88, 0x00, 0x00, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x00, 0x00, 0x00, 0x00, 0xff, 0xff,
+        0xff, 0x11, 0x00, 0x00, 0x00, 0x00, 0x00, 0xff, 0xff, 0xff, 0x33, 0x00, 0x00, 0x66, 0xff, 0xff,
+        0xff, 0xff, 0x88, 0x00, 0x00, 0x00, 0x00, 0xff, 0xff, 0xff, 0xff, 0x00, 0x00, 0xff, 0xff, 0xff
+    };
+
+    cv::Mat mat(10, 16, CV_8UC1, (void*)sample_data);
+    int methods[] = {
+        COMPRESSION_NONE,     COMPRESSION_LZW,
+        COMPRESSION_PACKBITS, COMPRESSION_DEFLATE,  COMPRESSION_ADOBE_DEFLATE
+    };
+    for (size_t i = 0; i < sizeof(methods) / sizeof(int); i++)
+    {
+        string out = cv::tempfile(".tif");
+
+        std::vector<int> params;
+        params.push_back(TIFFTAG_COMPRESSION);
+        params.push_back(methods[i]);
+        params.push_back(TIFFTAG_PREDICTOR);
+        params.push_back(PREDICTOR_HORIZONTAL);
+
+        EXPECT_NO_THROW(cv::imwrite(out, mat, params));
+
+        const Mat img = cv::imread(out, IMREAD_UNCHANGED);
+        ASSERT_FALSE(img.empty());
+
+        ASSERT_EQ(0, cv::norm(mat, img, cv::NORM_INF));
+
+        EXPECT_EQ(0, remove(out.c_str()));
+    }
+}
 
 //==================================================================================================