Sample program to extract a Minolta thumbnail from the makernote

// ***************************************************************** -*- C++ -*-
// mrwthumb.cpp
// Sample program to extract a Minolta thumbnail from the makernote
* Copyright (C) 2004-2021 Exiv2 authors
* This program is part of the Exiv2 distribution.
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* GNU General Public License for more details.
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, 5th Floor, Boston, MA 02110-1301 USA.
#include <exiv2/exiv2.hpp>
#include <cassert>
#include <iostream>
int main(int argc, char* const argv[])
try {
if (argc != 2) {
std::cout << "Usage: " << argv[0] << " file\n";
return 1;
assert(image.get() != 0);
Exiv2::ExifData& exifData = image->exifData();
if (exifData.empty()) {
std::string error(argv[1]);
error += ": No Exif data found in the file";
throw Exiv2::Error(Exiv2::kerErrorMessage, error);
Exiv2::ExifKey key("Exif.Minolta.ThumbnailOffset");
Exiv2::ExifData::const_iterator format = exifData.findKey(key);
if (format != exifData.end()) {
Exiv2::DataBuf buf = format->dataArea();
// The first byte of the buffer needs to be patched
buf.pData_[0] = 0xff;
Exiv2::FileIo file("img_thumb.jpg");"wb");
file.write(buf.pData_, buf.size_);
return 0;
} catch (Exiv2::AnyError& e) {
std::cout << "Caught Exiv2 exception '" << e << "'\n";
return -1;
byte * pData_
Pointer to the buffer, 0 if none has been allocated.
Definition: types.hpp:258
Provides binary file IO by implementing the BasicIo interface.
Definition: basicio.hpp:296
ExifMetadata::const_iterator const_iterator
ExifMetadata const iterator type.
Definition: exif.hpp:439
static bool initialize(XmpParser::XmpLockFct xmpLockFct=0, void *pLockData=0)
Initialize the XMP Toolkit.
Error class interface. Allows the definition and use of a hierarchy of error classes which can all be...
Definition: error.hpp:174
iterator end()
End of the metadata.
Definition: exif.hpp:492
Utility class containing a character array. All it does is to take care of memory allocation and dele...
Definition: types.hpp:193
Concrete keys for Exif metadata and access to Exif tag reference data.
Definition: tags.hpp:140
long size_
The current size of the buffer.
Definition: types.hpp:260
static void terminate()
Terminate the XMP Toolkit and unregister custom namespaces.
virtual int close()
Flush and unwritten data and close the file . It is safe to call close on an already closed instance.
bool empty() const
Return true if there is no Exif metadata.
Definition: exif.hpp:512
std::auto_ptr< Image > AutoPtr
Image auto_ptr type.
Definition: image.hpp:81
static Image::AutoPtr open(const std::string &path, bool useCurl=true)
Create an Image subclass of the appropriate type by reading the specified file. Image type is derived...
BasicError< char > Error
Error class used for exceptions (std::string based)
Definition: error.hpp:324
iterator findKey(const ExifKey &key)
Find the first Exifdatum with the given key, return an iterator to it.
virtual long write(const byte *data, long wcount)
Write data to the file. The file position is advanced by the number of bytes written.
int open(const std::string &mode)
Open the file using using the specified mode.
A container for Exif data. This is a top-level class of the Exiv2 library. The container holds Exifda...
Definition: exif.hpp:434