Updating of DNG files

[sinus007]

Hi,
Recently I noticed that it takes about 50% longer to update DNG files than PEF files (I'm using Pentax K-3).
I ran a quick test: copied n files of aprox. the same size of both formats into a folder that was being scanned and noticed this difference.
Is it due to a different structure of the files or how Imatch deals with them or something else?
Thanks in advance.

AK

[Mario]

I assume you meaning writing back metadata?
Without a log file I can only guess.

Try updating each file twice. Depending on which metadata you have changed, and the structure of the file before the write-back, ExifTool may need to splice the DNG file in order to make 'room' for the new metadata. Or maybe the PEF file was still in the file system cache but the DNG was 'cold' and had to be loaded. It's really hard to tell without more info. I don't even know if writing the PEF took one second and the DNG two, or if the PEF took 10s and the DNG 20s...

Lookup the term log file in the IMatch help for information about the IMatch log file and how you can use it (e.g. by attaching one here) to diagnose problems or other issues.

[ubacher]

Metadata for dng files is written directly into the dng file (no XMP needed).
I assume for the PEF file IM only needs to write an XMP file.
This would explain the difference.
At least that is how I see this.

[Richard]

Metadata for dng files is written directly into the dng file (no XMP needed).

It seems very strange to me that Adobe would not utilize XMP in their DNG format.

[Mario]

As I said, it's hard to tell without additional info.

A DNG file may contain EXIF, legacy IPTC and embedded XMP.

If the user updates XMP data for the DNG, IMatch thus has to change the metadata in the DNG file, which can be expensive (slow) because to much data needs to be read and written.

If the user updates XMP data for a PEF file, and the PEF file has no embedded EXIF or IPTC, IMatch only needs to update the sidecar file, which is of course blazing fast compared to the massive amount of data that needs to be shuffled around when updating a DNG file.

[lnh]

Metadata for dng files is written directly into the dng file (no XMP needed).

It seems very strange to me that Adobe would not utilize XMP in their DNG format.

They do use XMP inside the files. Makes sense in an archival format like DNG you'd want to keep all the data together. Choose the option to embed your original RAW file as well and you end up with HUGE files. Clearly a trade-off vs tiny sidecars for working with metadata.

[cytochrome]

Instead of stuffing image bitmap + Exif + xmp + raw + into DNG you can also write the xmp directly into the raw. Smaller file and self-contained...

Imatch (Exiftool) does it well. I use it for NEF, RW2 and MRW

Francis