Merge pull request #8492 from brian-armstrong-discord:exif_inmemory

autorotate in-memory jpegs (#8492)

* autorotate in-memory jpegs

* correct indentation (4 spaces)

* imgcodecs: don't apply EXIF rotation for unloaded images

* videoio: don't try to rotate MJPEG stream

* imgcodecs: ByteStreamBuffer::seekoff support all seek "dir"

* imgcodecs: fix condition: "off == egptr() - eback()" is valid offset

modules/imgcodecs/src/exif.cpp

@@ -61,7 +61,7 @@ ExifEntry_t::ExifEntry_t() :
 /**
  * @brief ExifReader constructor
  */
-ExifReader::ExifReader(std::string filename) : m_filename(filename), m_format(NONE)
+ExifReader::ExifReader(std::istream& stream) : m_stream(stream), m_format(NONE)
 {
 }
 
@@ -121,29 +121,18 @@ ExifEntry_t ExifReader::getTag(const ExifTagName tag)
  */
 std::map<int, ExifEntry_t > ExifReader::getExif()
 {
-    const size_t markerSize = 2;
+    const std::streamsize markerSize = 2;
-    const size_t offsetToTiffHeader = 6; //bytes from Exif size field to the first TIFF header
+    const std::streamsize offsetToTiffHeader = 6; //bytes from Exif size field to the first TIFF header
     unsigned char appMarker[markerSize];
     m_exif.erase( m_exif.begin(), m_exif.end() );
 
-    size_t count;
+    std::streamsize count;
-
-    if (m_filename.size() == 0)
-    {
-        return m_exif;
-    }
-
-    FILE* f = fopen( m_filename.c_str(), "rb" );
-
-    if( !f )
-    {
-        return m_exif; //Until this moment the map is empty
-    }
 
     bool exifFound = false, stopSearch = false;
-    while( ( !feof( f ) ) && !exifFound && !stopSearch )
+    while( ( !m_stream.eof() ) && !exifFound && !stopSearch )
     {
-        count = fread( appMarker, sizeof(unsigned char), markerSize, f );
+        m_stream.read( reinterpret_cast<char*>(appMarker), markerSize );
+        count = m_stream.gcount();
         if( count < markerSize )
         {
             break;
@@ -159,12 +148,14 @@ std::map<int, ExifEntry_t > ExifReader::getExif()
             case APP0: case APP2: case APP3: case APP4: case APP5: case APP6: case APP7: case APP8:
             case APP9: case APP10: case APP11: case APP12: case APP13: case APP14: case APP15:
             case COM:
-                bytesToSkip = getFieldSize( f );
+                bytesToSkip = getFieldSize();
                 if (bytesToSkip < markerSize) {
-                    fclose(f);
                     throw ExifParsingError();
                 }
-                fseek( f, static_cast<long>( bytesToSkip - markerSize ), SEEK_CUR );
+                m_stream.seekg( static_cast<long>( bytesToSkip - markerSize ), m_stream.cur );
+                if ( m_stream.fail() ) {
+                    throw ExifParsingError();
+                }
                 break;
 
             //SOI and EOI don't have the size field after the marker
@@ -172,14 +163,17 @@ std::map<int, ExifEntry_t > ExifReader::getExif()
                 break;
 
             case APP1: //actual Exif Marker
-                exifSize = getFieldSize(f);
+                exifSize = getFieldSize();
                 if (exifSize <= offsetToTiffHeader) {
-                    fclose(f);
                     throw ExifParsingError();
                 }
                 m_data.resize( exifSize - offsetToTiffHeader );
-                fseek(f, static_cast<long>( offsetToTiffHeader ), SEEK_CUR);
+                m_stream.seekg( static_cast<long>( offsetToTiffHeader ), m_stream.cur );
-                count = fread( &m_data[0], sizeof( unsigned char ), exifSize - offsetToTiffHeader, f );
+                if ( m_stream.fail() ) {
+                    throw ExifParsingError();
+                }
+                m_stream.read( reinterpret_cast<char*>(&m_data[0]), exifSize - offsetToTiffHeader );
+                count = m_stream.gcount();
                 exifFound = true;
                 break;
 
@@ -189,8 +183,6 @@ std::map<int, ExifEntry_t > ExifReader::getExif()
         }
     }
 
-    fclose(f);
-
     if( !exifFound )
     {
         return m_exif;
@@ -207,10 +199,11 @@ std::map<int, ExifEntry_t > ExifReader::getExif()
  *
  *  @return size of exif field in the file
  */
-size_t ExifReader::getFieldSize (FILE* f) const
+size_t ExifReader::getFieldSize ()
 {
     unsigned char fieldSize[2];
-    size_t count = fread ( fieldSize, sizeof( char ), 2, f );
+    m_stream.read( reinterpret_cast<char*>(fieldSize), 2 );
+    std::streamsize count = m_stream.gcount();
     if (count < 2)
     {
         return 0;

modules/imgcodecs/src/exif.hpp

@@ -51,6 +51,7 @@
 #include <stdint.h>
 #include <string>
 #include <vector>
+#include <iostream>
 
 namespace cv
 {
@@ -168,9 +169,9 @@ public:
     /**
      * @brief ExifReader constructor. Constructs an object of exif reader
      *
-     * @param [in]filename The name of file to look exif info in
+     * @param [in]stream An istream to look for EXIF bytes from
      */
-    explicit ExifReader( std::string filename );
+    explicit ExifReader( std::istream& stream );
     ~ExifReader();
 
 
@@ -190,7 +191,7 @@ public:
     ExifEntry_t getTag( const ExifTagName tag );
 
 private:
-    std::string m_filename;
+    std::istream& m_stream;
     std::vector<unsigned char> m_data;
     std::map<int, ExifEntry_t > m_exif;
     Endianess_t m_format;
@@ -198,7 +199,7 @@ private:
     void parseExif();
     bool checkTagMark() const;
 
-    size_t getFieldSize ( FILE* f ) const;
+    size_t getFieldSize ();
     size_t getNumDirEntry() const;
     uint32_t getStartOffset() const;
     uint16_t getExifTag( const size_t offset ) const;
@@ -247,7 +248,6 @@ private:
 };
 
 
-
 }
 
 #endif /* _OPENCV_EXIF_HPP_ */

modules/imgcodecs/src/loadsave.cpp

@@ -50,10 +50,50 @@
 #undef min
 #undef max
 #include <iostream>
+#include <fstream>
 
 /****************************************************************************************\
 *                                      Image Codecs                                      *
 \****************************************************************************************/
+namespace {
+
+class ByteStreamBuffer: public std::streambuf
+{
+public:
+    ByteStreamBuffer(char* base, size_t length)
+    {
+        setg(base, base, base + length);
+    }
+
+protected:
+    virtual pos_type seekoff( off_type offset,
+                              std::ios_base::seekdir dir,
+                              std::ios_base::openmode )
+    {
+        // get absolute offset
+        off_type off = offset;
+        if (dir == std::ios_base::cur)
+        {
+            off += gptr() - eback();
+        }
+        else if (dir == std::ios_base::end)
+        {
+            off += egptr() - eback();
+        }
+
+        // check limits
+        if (off >= (off_type)0 && off <= egptr() - eback())
+        {
+            setg(eback(), gptr() + off, egptr());
+            return gptr() - eback();
+        }
+
+        return -1;
+    }
+};
+
+}
+
 namespace cv
 {
 
@@ -232,23 +272,8 @@ static ImageEncoder findEncoder( const String& _ext )
 
 enum { LOAD_CVMAT=0, LOAD_IMAGE=1, LOAD_MAT=2 };
 
-static void ApplyExifOrientation(const String& filename, Mat& img)
+static void ExifTransform(int orientation, Mat& img)
 {
-    int orientation = IMAGE_ORIENTATION_TL;
-
-    if (filename.size() > 0)
-    {
-        ExifReader reader( filename );
-        if( reader.parse() )
-        {
-            ExifEntry_t entry = reader.getTag( ORIENTATION );
-            if (entry.tag != INVALID_TAG)
-            {
-                orientation = entry.field_u16; //orientation is unsigned short, so check field_u16
-            }
-        }
-    }
-
     switch( orientation )
     {
         case    IMAGE_ORIENTATION_TL: //0th row == visual top, 0th column == visual left-hand side
@@ -284,6 +309,50 @@ static void ApplyExifOrientation(const String& filename, Mat& img)
     }
 }
 
+static void ApplyExifOrientation(const String& filename, Mat& img)
+{
+    int orientation = IMAGE_ORIENTATION_TL;
+
+    if (filename.size() > 0)
+    {
+        std::ifstream stream( filename.c_str(), std::ios_base::in | std::ios_base::binary );
+        ExifReader reader( stream );
+        if( reader.parse() )
+        {
+            ExifEntry_t entry = reader.getTag( ORIENTATION );
+            if (entry.tag != INVALID_TAG)
+            {
+                orientation = entry.field_u16; //orientation is unsigned short, so check field_u16
+            }
+        }
+        stream.close();
+    }
+
+    ExifTransform(orientation, img);
+}
+
+static void ApplyExifOrientation(const Mat& buf, Mat& img)
+{
+    int orientation = IMAGE_ORIENTATION_TL;
+
+    if( buf.isContinuous() )
+    {
+        ByteStreamBuffer bsb( reinterpret_cast<char*>(buf.data), buf.total() * buf.elemSize() );
+        std::istream stream( &bsb );
+        ExifReader reader( stream );
+        if( reader.parse() )
+        {
+            ExifEntry_t entry = reader.getTag( ORIENTATION );
+            if (entry.tag != INVALID_TAG)
+            {
+                orientation = entry.field_u16; //orientation is unsigned short, so check field_u16
+            }
+        }
+    }
+
+    ExifTransform(orientation, img);
+}
+
 /**
  * Read an image into memory and return the information
  *
@@ -494,7 +563,7 @@ Mat imread( const String& filename, int flags )
     imread_( filename, flags, LOAD_MAT, &img );
 
     /// optionally rotate the data if EXIF' orientation flag says so
-    if( (flags & IMREAD_IGNORE_ORIENTATION) == 0 && flags != IMREAD_UNCHANGED )
+    if( !img.empty() && (flags & IMREAD_IGNORE_ORIENTATION) == 0 && flags != IMREAD_UNCHANGED )
     {
         ApplyExifOrientation(filename, img);
     }
@@ -658,6 +727,13 @@ Mat imdecode( InputArray _buf, int flags )
 {
     Mat buf = _buf.getMat(), img;
     imdecode_( buf, flags, LOAD_MAT, &img );
+
+    /// optionally rotate the data if EXIF' orientation flag says so
+    if( !img.empty() && (flags & IMREAD_IGNORE_ORIENTATION) == 0 && flags != IMREAD_UNCHANGED )
+    {
+        ApplyExifOrientation(buf, img);
+    }
+
     return img;
 }
 
@@ -666,6 +742,13 @@ Mat imdecode( InputArray _buf, int flags, Mat* dst )
     Mat buf = _buf.getMat(), img;
     dst = dst ? dst : &img;
     imdecode_( buf, flags, LOAD_MAT, dst );
+
+    /// optionally rotate the data if EXIF' orientation flag says so
+    if( !dst->empty() && (flags & IMREAD_IGNORE_ORIENTATION) == 0 && flags != IMREAD_UNCHANGED )
+    {
+        ApplyExifOrientation(buf, *dst);
+    }
+
     return *dst;
 }
 

modules/videoio/src/cap_mjpeg_decoder.cpp

@@ -821,7 +821,7 @@ bool MotionJpegCapture::retrieveFrame(int, OutputArray output_frame)
 
         if(data.size())
         {
-            m_current_frame = imdecode(data, CV_LOAD_IMAGE_ANYDEPTH | CV_LOAD_IMAGE_COLOR);
+            m_current_frame = imdecode(data, CV_LOAD_IMAGE_ANYDEPTH | CV_LOAD_IMAGE_COLOR | IMREAD_IGNORE_ORIENTATION);
         }
 
         m_current_frame.copyTo(output_frame);