Added EXIF output support for JPEG, WebP and AVIF format writers.

Reading of EXIF data is, however, only currently supported by the JPEG input reader, so no TIFF EXIF input support for the moment.

ChangeLog

@@ -1,3 +1,8 @@
+28/10/2024:
+	- Added EXIF output support for JPEG, WebP and AVIF format writers. Reading of EXIF data is, however, only
+	  currently supported by the JPEG input reader, so no TIFF EXIF input support for the moment.
+
+
 27/10/2024:
 	- Added ability to inject ICC profile and XMP metadata into pre-encoded tiles returned from TIFF images. These
 	  are essentially raw bitstreams with no container. Works for both JPEG and WebP formats.

src/AVIFCompressor.cc

@@ -164,6 +164,7 @@ unsigned int AVIFCompressor::Compress( RawTile& rawtile ){
   // Add ICC profile and XMP metadata to our image
   writeICCProfile();
   writeXMPMetadata();
+  writeExifMetadata();
 
 
   if( (OK=avifEncoderAddImage( encoder, avif, 1, AVIF_ADD_IMAGE_FLAG_SINGLE )) != AVIF_RESULT_OK ){
@@ -238,3 +239,21 @@ void AVIFCompressor::writeXMPMetadata()
   }
 #endif
 }
+
+
+
+/// Write EXIF metadata
+void AVIFCompressor::writeExifMetadata()
+{
+  size_t len = exif.size();
+  if( len == 0 ) return;
+
+#if AVIF_VERSION_MAJOR < 1
+  // No return from version < 1
+  avifImageSetMetadataExif( avif, (const uint8_t*) exif.c_str(), len );
+#else
+  if( avifImageSetMetadataExif( avif, (const uint8_t*) exif.c_str(), len ) != AVIF_RESULT_OK ){
+    throw string( "AVIFCompressor :: Error adding EXIF metadata" );
+  }
+#endif
+}

src/AVIFCompressor.h

@@ -52,6 +52,9 @@ class AVIFCompressor : public Compressor {
   /// Write XMP metadata
   void writeXMPMetadata();
 
+  /// Write EXIF metadata
+  void writeExifMetadata();
+
 
  public:
 

src/CVT.cc

@@ -536,6 +536,15 @@ void CVT::send( Session* session ){
     compressor->embedXMPMetadata( true );
   }
 
+  // Always embed EXIF metadata in CVT function
+  if( (*session->image)->getMetadata("exif").size() > 0 ){
+    if( session->loglevel >= 3 ){
+      *(session->logfile) << "CVT :: Embedding EXIF metadata with size "
+			  << (*session->image)->getMetadata("exif").size() << " bytes" << endl;
+    }
+    compressor->embedExifMetadata( true );
+  }
+
 
   // Initialise our output compression object
   compressor->InitCompression( complete_image, resampled_height );

src/Compressor.h

@@ -62,6 +62,10 @@ class Compressor {
   bool embedXMP;
   std::string xmp;
 
+  // EXIF metadata
+  bool embedEXIF;
+  std::string exif;
+
   /// Write metadata
   virtual void writeMetadata() {};
 
@@ -74,6 +78,9 @@ class Compressor {
   /// Write XMP metadata
   virtual void writeXMPMetadata() {};
 
+  /// Write EXIF metadata
+  virtual void writeExifMetadata() {};
+
 
  public:
 
@@ -88,7 +95,8 @@ class Compressor {
     dpi_y( 0 ),
     dpi_units( 0 ),
     embedICC( false ),
-    embedXMP( false ) {};
+    embedXMP( false ),
+    embedEXIF( false ) {};
 
 
   virtual ~Compressor() {};
@@ -125,6 +133,9 @@ class Compressor {
   /** @param embed Whether XMP metadata should be embedded */
   inline void embedXMPMetadata( const bool embed ){ this->embedXMP = embed; }
 
+  /// Embed EXIF metadata
+  /** @param embed Whether EXIF metadata should be embedded */
+  inline void embedExifMetadata( const bool embed ){ this->embedEXIF = embed; }
 
   /// Set general metadata
   /** @param metadata Metadata list */
@@ -146,9 +157,21 @@ class Compressor {
       xmp = it->second;
       this->metadata.erase( it );
     }
+
+    // Extract EXIF chunk if it exists and remove from list
+    it = this->metadata.find("exif");
+    if( it != this->metadata.end() ){
+      exif = it->second;
+      this->metadata.erase( it );
+    }
+
   };
 
 
+  /// Set quality level
+  /** @param quality quality level */
+  virtual void setQuality( int quality ) {};
+
 
   /// Initialise strip based compression
   /** If we are doing a strip based encoding, we need to first initialise

src/JPEGCompressor.cc

@@ -55,6 +55,9 @@ inline double round(double r) { return (r > 0.0) ? floor(r + 0.5) : ceil(r - 0.5
 #define XMP_PREFIX "http://ns.adobe.com/xap/1.0/%c%s"
 #define XMP_PREFIX_SIZE 29
 
+// EXIF definitions
+#define EXIF_PREFIX "Exif\0\0"
+#define EXIF_PREFIX_SIZE 6
 
 
 /* IIPImage version of the JPEG error_exit function. We want to pass control back
@@ -82,7 +85,7 @@ extern "C" {
    *  way of doing this, but this seems to work :/
    */
   void setup_error_functions( jpeg_compress_struct *a ){
-    a->err->error_exit = iip_error_exit; 
+    a->err->error_exit = iip_error_exit;
   }
 }
 
@@ -185,7 +188,8 @@ void JPEGCompressor::InitCompression( const RawTile& rawtile, unsigned int strip
   // Calculate our metadata storage requirements
   unsigned int metadata_size =
     (icc.size()>0 ? (icc.size()+ICC_OVERHEAD_LEN) : 0) +
-    (xmp.size()>0 ? (xmp.size()+XMP_PREFIX_SIZE) : 0);
+    (xmp.size()>0 ? (xmp.size()+XMP_PREFIX_SIZE) : 0) +
+    (exif.size()>0 ? (exif.size()+EXIF_PREFIX_SIZE) : 0);
 
   // Allocate enough memory for our header and metadata
   unsigned long output_size = metadata_size + MX;
@@ -225,7 +229,10 @@ void JPEGCompressor::InitCompression( const RawTile& rawtile, unsigned int strip
 
   // Add XMP metadata
   writeXMPMetadata();
-
+
+  // Add EXIF metadata
+  writeExifMetadata();
+
   // Copy the encoded JPEG header data to a separate buffer
   size_t datacount = dest->source_size - dest->pub.free_in_buffer;
   header_size = datacount;
@@ -337,7 +344,8 @@ unsigned int JPEGCompressor::Compress( RawTile& rawtile )
   // Calculate our metadata storage requirements
   unsigned int metadata_size =
     (icc.size()>0 ? (icc.size()+ICC_OVERHEAD_LEN) : 0) +
-    (xmp.size()>0 ? (xmp.size()+XMP_PREFIX_SIZE) : 0);
+    (xmp.size()>0 ? (xmp.size()+XMP_PREFIX_SIZE) : 0) +
+    (exif.size()>0 ? (exif.size()+EXIF_PREFIX_SIZE) : 0);
 
   // Allocate enough memory for our compressed output data
   // - compressed images at overly high quality factors can be larger than raw data
@@ -373,6 +381,9 @@ unsigned int JPEGCompressor::Compress( RawTile& rawtile )
   // Add XMP metadata
   writeXMPMetadata();
 
+  // Add EXIF metadata
+  writeExifMetadata();
+
 
   // Compress the image line by line
   JSAMPROW row[1];
@@ -516,9 +527,27 @@ void JPEGCompressor::writeXMPMetadata()
 
 
 
+void JPEGCompressor::writeExifMetadata()
+{
+  // Skip if EXIF embedding is disabled or no EXIF present
+  if( !embedEXIF || exif.empty() ) return;
+
+  size_t len = exif.size();
+
+  // Need to add prefix (need do this with memcpy because of null bytes)
+  char exifstr[65536];
+  memcpy( exifstr, EXIF_PREFIX, EXIF_PREFIX_SIZE );
+  memcpy( exifstr+EXIF_PREFIX_SIZE, exif.c_str(), len );
+
+  // Write out our marker
+  jpeg_write_marker( &cinfo, JPEG_APP0+1, (const JOCTET*) exifstr, len+EXIF_PREFIX_SIZE );
+}
+
+
+
 void JPEGCompressor::injectMetadata( RawTile& rawtile )
 {
-  if( (!embedICC && !embedXMP) || (icc.empty() && xmp.empty()) ) return;
+  if( (!embedICC && !embedXMP &&!embedEXIF) || (icc.empty() && xmp.empty() && exif.empty()) ) return;
 
   // Initialize our compression structure
   InitCompression( rawtile, 0 );

src/JPEGCompressor.h

@@ -78,6 +78,9 @@ class JPEGCompressor: public Compressor{
   /// Write XMP metadata
   void writeXMPMetadata();
 
+  /// Write EXIF metadata
+  void writeExifMetadata();
+
 
  public:
 

src/PNGCompressor.cc

@@ -105,7 +105,8 @@ void PNGCompressor::InitCompression( const RawTile& rawtile, unsigned int strip_
   // Calculate our metadata storage requirements
   unsigned int metadata_size =
     (icc.size()>0 ? (icc.size()+ICC_OVERHEAD_SIZE) : 0) +
-    (xmp.size()>0 ? (xmp.size()+XMP_OVERHEAD_SIZE) : 0);
+    (xmp.size()>0 ? (xmp.size()+XMP_OVERHEAD_SIZE) : 0) +
+    (exif.size()>0 ? exif.size() : 0);
 
   // Allocate enough memory for our header and metadata
   unsigned long output_size = metadata_size + MX;
@@ -243,7 +244,8 @@ unsigned int PNGCompressor::Compress( RawTile& rawtile )
   // Calculate our metadata storage requirements
   unsigned int metadata_size =
     (icc.size()>0 ? (icc.size()+ICC_OVERHEAD_SIZE) : 0) +
-    (xmp.size()>0 ? (xmp.size()+XMP_OVERHEAD_SIZE) : 0);
+    (xmp.size()>0 ? (xmp.size()+XMP_OVERHEAD_SIZE) : 0) +
+    (exif.size()>0) ? exif.size() : 0;
 
   // Allocate enough memory for our compressed output data - make sure there is extra buffering
   // Note that compressed images at overly high quality factors can be larger than raw data
@@ -412,6 +414,9 @@ void PNGCompressor::writeMetadata()
 
   // Write XMP chunk
   writeXMPMetadata();
+
+  // Write EXIF chunk
+  writeExifMetadata();
 }
 
 
@@ -474,3 +479,17 @@ void PNGCompressor::writeXMPMetadata()
   png_set_text( dest.png_ptr, dest.info_ptr, &text, 1 );
 
 }
+
+
+
+void PNGCompressor::writeExifMetadata()
+{
+  // Skip if EXIF embedding is disabled or no EXIF present
+  if( !embedEXIF || exif.empty() ) return;
+
+#ifdef PNG_eXIf_SUPPORTED
+  // Write out EXIF chunk
+  png_set_eXIf_1( dest.png_ptr, dest.info_ptr, exif.size(), (png_bytep) exif.c_str() );
+#endif
+
+}

src/PNGCompressor.h

@@ -80,7 +80,10 @@ class PNGCompressor : public Compressor {
   /// Write XMP metadata
   void writeXMPMetadata();
 
-
+  /// Write EXIF metadata
+  void writeExifMetadata();
+
+
  public:
 
   /// Constructor

src/WebPCompressor.cc

@@ -126,12 +126,13 @@ unsigned int WebPCompressor::Compress( RawTile& rawtile ){
   WebPData output;
 
   // Use the WebP muxer only if we need to
-  if( icc.size() > 0 || xmp.size() > 0 ){
+  if( icc.size() > 0 || xmp.size() > 0 || exif.size() > 0 ){
 
     // Add ICC profile and XMP metadata to our output bitstream
     writeICCProfile();
     writeXMPMetadata();
-
+    writeExifMetadata();
+
     // Add our image data chunk
     WebPData chunk;
     chunk.bytes = writer.mem;
@@ -213,15 +214,32 @@ void WebPCompressor::writeXMPMetadata()
 
 
 
+/// Write EXIF metadata
+void WebPCompressor::writeExifMetadata()
+{
+  // Skip if EXIF embedding disabled or no EXIF chunk exists
+  if( !embedEXIF || exif.empty() ) return;
+
+  WebPData chunk;
+  chunk.bytes = (const uint8_t*) exif.c_str();
+  chunk.size = exif.size();
+
+  if( WebPMuxSetChunk( mux, "EXIF", &chunk, 0 ) != WEBP_MUX_OK ){
+    throw string( "WebPCompressor :: Error setting EXIF chunk" );
+  }
+}
+
+
+
 void WebPCompressor::injectMetadata( RawTile& rawtile )
 {
-  if( (!embedICC && !embedXMP) || (icc.empty() && xmp.empty()) ) return;
+  if( (!embedICC && !embedXMP && !embedEXIF) || (icc.empty() && xmp.empty() && exif.empty()) ) return;
 
   WebPData input;
   input.bytes = (const uint8_t*) rawtile.data;
   input.size = rawtile.dataLength;
 
-  // Only add ICC or metadata if we have a raw WebP stream
+  // Only add ICC or metadata if we have a raw WebP stream:
   // Bytes 8-16 should be exactly "WEBPVP8 " (lossy) or "WEBPVP8L" (lossless)
   static const unsigned char lossy_header[8] = {0x57,0x45,0x42,0x50,0x56,0x50,0x38,0x20};
   static const unsigned char lossless_header[8] = {0x57,0x45,0x42,0x50,0x56,0x50,0x38,0x4c};
@@ -231,9 +249,10 @@ void WebPCompressor::injectMetadata( RawTile& rawtile )
 
     WebPData output;
 
-    // Add ICC profile and XMP metadata to our output bitstream
+    // Add ICC profile, XMP and EXIF metadata to our output bitstream
     writeICCProfile();
     writeXMPMetadata();
+    writeExifMetadata();
 
     // Add our raw image bitstream data
     if( WebPMuxSetImage( mux, &input, 0 ) != WEBP_MUX_OK ){

src/WebPCompressor.h

@@ -53,6 +53,9 @@ class WebPCompressor : public Compressor {
   /// Write XMP metadata
   void writeXMPMetadata();
 
+  /// Write EXIF metadata
+  void writeExifMetadata();
+
 
  public: