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Extract XMP data from embedded JPEG preview inside RAF files

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The Fujifilm X-T5 camera stores in-camera rating for RAF images
by using XMP. But the XMP data is not directly encoded into the
RAF structure - instead it is attached as a second APP1 segment
to the embedded JPEG preview file.

This patch extracts the JPEG preview and parses it like a standalone
JPEG file.
This commit is contained in:
Daniel Vogelbacher 2023-05-10 22:17:07 +02:00
parent c86ae6acf5
commit 6c4b6d9d7f
1 changed files with 20 additions and 5 deletions
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25
src/rafimage.cpp
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@ -10,6 +10,7 @@
#include "futils.hpp"
#include "image.hpp"
#include "image_int.hpp"
#include "jpgimage.hpp"
#include "safe_op.hpp"
#include "tiffimage.hpp"
@ -248,17 +249,31 @@ void RafImage::readMetadata() {
Internal::enforce(jpg_img_len >= 12, ErrorCode::kerCorruptedMetadata);
DataBuf buf(jpg_img_len - 12);
if (io_->seek(jpg_img_off + 12, BasicIo::beg) != 0)
DataBuf jpg_buf(jpg_img_len);
if (io_->seek(jpg_img_off, BasicIo::beg) != 0)
throw Error(ErrorCode::kerFailedToReadImageData);
if (!buf.empty()) {
io_->read(buf.data(), buf.size());
if (!jpg_buf.empty()) {
io_->read(jpg_buf.data(), jpg_buf.size());
if (io_->error() || io_->eof())
throw Error(ErrorCode::kerFailedToReadImageData);
}
ByteOrder bo = TiffParser::decode(exifData_, iptcData_, xmpData_, buf.c_data(), buf.size());
// Extracting metadata from first APP1 container
constexpr byte tiff_offset = 12;
ByteOrder bo = TiffParser::decode(exifData_, iptcData_, xmpData_, jpg_buf.c_data() + tiff_offset, jpg_buf.size() - tiff_offset);
// If there is no XMP data in first APP1 EXIF structure, there is maybe
// another APP1 container for XMP. Just use the JpegImage metadata parser for that.
if(xmpData_.empty()) {
auto jpg_io = std::make_unique<Exiv2::MemIo>(jpg_buf.data(), jpg_buf.size());
auto jpg_img = JpegImage(std::move(jpg_io), false);
jpg_img.readMetadata();
const auto jpg_xmp_data = jpg_img.xmpData();
for(auto& datum : jpg_xmp_data) {
xmpData_.add(datum);
}
}
exifData_["Exif.Image2.JPEGInterchangeFormat"] = getULong(jpg_img_offset, bigEndian);
exifData_["Exif.Image2.JPEGInterchangeFormatLength"] = getULong(jpg_img_length, bigEndian);