[IM2020] Prevent modifying Sony ARW

[Rene Toepfer]

How can I prevent that the Sony RAW (ARW) files will be modified while write-back? If I look at the help, this comes up: "This behavior is of especial importance when you work with RAW files. If you update XMP metadata for a RAW file, this XMP data is usually stored in a sidecar file. The RAW file is not modified when you edit metadata. Only when the RAW file already contains IPTC and EXIF data, this data is updated by IMatch. But IMatch does not create new IPTC records in RAW files." (https://www.photools.com/help/imatch/#md_writeback.htm?dl=h-9)
Would it be possible to prevent IM to write-back even these data into ARW file and write-back into sidecar file instead?

The settings for the ARW file format is as per standard, see attachement.

[Mario]

IMatch writes XMP data into the sidecar for RAW files.
IMatch embeds XMP in file formats which are standardized to contain XMP: JPG, TIF, PSD, PSB, PNG, GIF, DNG.

Since XMP contains copies of EXIF, legacy IPTC and GPS data in your RAW file, IMatch lets ExifTool synchronize changes done to XMP back into the corresponding native data.
That's called Metadata Working Group compatibility and ensures that the metadata in your files and the XMP data is always in sync.

IMatch does this since 2015.
I don't recommend changing this behavior. IMatch has options to break this synchronization (see help) but I nether endorse nor support this.

[Rene Toepfer]

OK, if it is a standardized proceeding to write-back XMP in RAW files it is fine to me. I just wanted to make sure not having wrong settings. My main concern is that the RAW file gets corrupt while writing-back. Do you or anybody else have experiences with this? Until now I have never changed a RAW file.

[Mario]

No, XMP data is not written to the RAW, it is written to a separate XMP sidecar file. This is how it is in the standard.
EXIF and legacy and GPS metadata exists twice: once in the RAW and, as mapped copies, in the XMP. Hence the need to synchronize forth and back.

Recently some camera vendors started to add XMP directly to the RAW. Usually, an incomplete XMP record containing only the rating=none field.
Probably to support some in-camera rating or similar.
And this creates a new set of problems, e.g having two XMP records for a RAW. The standard record in the XMP sidecar file and another XMP record in the RAW, with a hard-coded rating=none.
Why camera vendors still stick the problem-ridden and 30 year old EXIF metadata escapes me. They could store the same info as XMP, including all their proprietary and undocumented maker notes.

Until now I have never changed a RAW file.

A RAW is just a TIFF file, with a "heap" (data block) containing the Bayer mosaic data produced by your camera. All else is like any other TIF. There is nothing holy or secret with RAW files.

This discussion of whether or not the metadata in a RAW should be modified ran for years. And, frankly, unless you work for the police or insurance business and you have to maintain chain of evidence, it does not matter. And in these businesses, you are using special cameras with special RAW formats anyway.

Having different EXIF, legacy IPTC and GPS data in the image and the XMP causes way more problems. Best to keep everything in sync, nice and shiny.

[sinus]

OK, if it is a standardized proceeding to write-back XMP in RAW files it is fine to me. I just wanted to make sure not having wrong settings. My main concern is that the RAW file gets corrupt while writing-back. Do you or anybody else have experiences with this? Until now I have never changed a RAW file.

I have never had a corrupt raw (in my case nef), where IMatch has been guilty.
And I do all with IMatch 

I do not care, if the file is jpg, nef, psd or whatever. I simply trust IMatch ... and this since hmmm, oh, 20 years! 

[Mario]

I have updates all my 150,000 private NEF files with IMatch. And even removed legacy IPTC (IIM) data years ago, which Nikon insisted in writing with older Capture versions.
No file has ever failed to load in older and current RAW processors or image editors. Except when said RAW processor / image editor was buggy or messed up its metadata management.

[Rene Toepfer]

This sounds good, thanks for sharing your experiences. I will give it a try. With C1 I have not yet an issue with changed RAW files by Imatch. Only the preview cache will be rebuild for revised RAW if they will be loaded again. That was also the reason why I was wondering in the beginning and resulted in my opening question.