Merge remote-tracking branch 'upstream/3.4' into merge-3.4

modules/imgcodecs/include/opencv2/imgcodecs.hpp

@@ -62,7 +62,7 @@ namespace cv
 
 //! Imread flags
 enum ImreadModes {
-       IMREAD_UNCHANGED            = -1, //!< If set, return the loaded image as is (with alpha channel, otherwise it gets cropped).
+       IMREAD_UNCHANGED            = -1, //!< If set, return the loaded image as is (with alpha channel, otherwise it gets cropped). Ignore EXIF orientation.
        IMREAD_GRAYSCALE            = 0,  //!< If set, always convert image to the single channel grayscale image (codec internal conversion).
        IMREAD_COLOR                = 1,  //!< If set, always convert image to the 3 channel BGR color image.
        IMREAD_ANYDEPTH             = 2,  //!< If set, return 16-bit/32-bit image when the input has the corresponding depth, otherwise convert it to 8-bit.
@@ -172,8 +172,9 @@ Currently, the following file formats are supported:
     then the [GDAL](http://www.gdal.org) driver will be used in order to decode the image, supporting
     the following formats: [Raster](http://www.gdal.org/formats_list.html),
     [Vector](http://www.gdal.org/ogr_formats.html).
--   If EXIF information are embedded in the image file, the EXIF orientation will be taken into account
-    and thus the image will be rotated accordingly except if the flag @ref IMREAD_IGNORE_ORIENTATION is passed.
+-   If EXIF information is embedded in the image file, the EXIF orientation will be taken into account
+    and thus the image will be rotated accordingly except if the flags @ref IMREAD_IGNORE_ORIENTATION
+    or @ref IMREAD_UNCHANGED are passed.
 -   Use the IMREAD_UNCHANGED flag to keep the floating point values from PFM image.
 -   By default number of pixels must be less than 2^30. Limit can be set using system
     variable OPENCV_IO_MAX_IMAGE_PIXELS

modules/imgcodecs/src/loadsave.cpp

@@ -51,6 +51,8 @@
 #undef max
 #include <iostream>
 #include <fstream>
+#include <cerrno>
+#include <opencv2/core/utils/logger.hpp>
 #include <opencv2/core/utils/configuration.private.hpp>
 
 
@@ -693,6 +695,23 @@ static bool imwrite_( const String& filename, const std::vector<Mat>& img_vec,
             code = encoder->write( write_vec[0], params );
         else
             code = encoder->writemulti( write_vec, params ); //to be implemented
+
+        if (!code)
+        {
+            FILE* f = fopen( filename.c_str(), "wb" );
+            if ( !f )
+            {
+                if (errno == EACCES)
+                {
+                    CV_LOG_WARNING(NULL, "imwrite_('" << filename << "'): can't open file for writing: permission denied");
+                }
+            }
+            else
+            {
+                fclose(f);
+                remove(filename.c_str());
+            }
+        }
     }
     catch (const cv::Exception& e)
     {