Merge pull request #2378 from ngryman:progressive_jpeg

modules/highgui/include/opencv2/highgui.hpp

@@ -216,6 +216,7 @@ enum { IMREAD_UNCHANGED  = -1, // 8bit, color or not
      };
 
 enum { IMWRITE_JPEG_QUALITY     = 1,
+       IMWRITE_JPEG_PROGRESSIVE = 2,
        IMWRITE_PNG_COMPRESSION  = 16,
        IMWRITE_PNG_STRATEGY     = 17,
        IMWRITE_PNG_BILEVEL      = 18,

modules/highgui/include/opencv2/highgui/highgui_c.h

@@ -220,6 +220,7 @@ CVAPI(CvMat*) cvLoadImageM( const char* filename, int iscolor CV_DEFAULT(CV_LOAD
 enum
 {
     CV_IMWRITE_JPEG_QUALITY =1,
+    CV_IMWRITE_JPEG_PROGRESSIVE =2,
     CV_IMWRITE_PNG_COMPRESSION =16,
     CV_IMWRITE_PNG_STRATEGY =17,
     CV_IMWRITE_PNG_BILEVEL =18,

modules/highgui/src/grfmt_jpeg.cpp

@@ -598,6 +598,7 @@ bool JpegEncoder::write( const Mat& img, const std::vector<int>& params )
         cinfo.in_color_space = channels > 1 ? JCS_RGB : JCS_GRAYSCALE;
 
         int quality = 95;
+        int progressive = 0;
 
         for( size_t i = 0; i < params.size(); i += 2 )
         {
@@ -606,11 +607,18 @@ bool JpegEncoder::write( const Mat& img, const std::vector<int>& params )
                 quality = params[i+1];
                 quality = MIN(MAX(quality, 0), 100);
             }
+
+            if( params[i] == CV_IMWRITE_JPEG_PROGRESSIVE )
+            {
+                progressive = params[i+1];
+            }
         }
 
         jpeg_set_defaults( &cinfo );
         jpeg_set_quality( &cinfo, quality,
                           TRUE /* limit to baseline-JPEG values */ );
+        if( progressive )
+            jpeg_simple_progression( &cinfo );
         jpeg_start_compress( &cinfo, TRUE );
 
         if( channels > 1 )

modules/highgui/test/test_grfmt.cpp

@@ -386,6 +386,30 @@ TEST(Highgui_Jpeg, encode_empty)
 
     ASSERT_THROW(cv::imencode(".jpg", img, jpegImg), cv::Exception);
 }
+
+TEST(Highgui_Jpeg, encode_decode_progressive_jpeg)
+{
+    cvtest::TS& ts = *cvtest::TS::ptr();
+    string input = string(ts.get_data_path()) + "../cv/shared/lena.png";
+    cv::Mat img = cv::imread(input);
+    ASSERT_FALSE(img.empty());
+
+    std::vector<int> params;
+    params.push_back(IMWRITE_JPEG_PROGRESSIVE);
+    params.push_back(1);
+
+    string output_progressive = cv::tempfile(".jpg");
+    EXPECT_NO_THROW(cv::imwrite(output_progressive, img, params));
+    cv::Mat img_jpg_progressive = cv::imread(output_progressive);
+
+    string output_normal = cv::tempfile(".jpg");
+    EXPECT_NO_THROW(cv::imwrite(output_normal, img));
+    cv::Mat img_jpg_normal = cv::imread(output_normal);
+
+    EXPECT_EQ(0, cv::norm(img_jpg_progressive, img_jpg_normal, NORM_INF));
+
+    remove(output_progressive.c_str());
+}
 #endif