I have just started my evaluation of Photo Mechanic 4.5.3.1 for OS X (10.4.11 Intel).
Unfortunately it seems that many actions in PM modify my RAW files (mostly Canon CR2s and older CRWs). For example, soft rotating the image or adding a tag/color/rating changes the MD5 checksum of the RAW file. This happens even though in the preference I have set "Add tag, color class, and rating to IPTC/XMP" to "Never" and I have checked "Don't update embedded IPTC/IPTC4XMP even if it exists."
In fact, no matter how many file-modifying options I disable, it seems I can always find a way to make PM change the underlying RAW file. Even changing file permissions to read-only (chmod 400) doesn't stop PM from changing files.
For me this is unacceptable because I treat my RAW files as immutable read-only negatives. I'll tolerate data being added to a sidecar file, but modifications to the RAW file itself are a no-no.
This is more than a casual preference. I archive my RAW files with MD5 checksums, and if a careless action in PM can modify a file, I lose the ability to detect real data corruption. Furthermore, when PM touches a file, it causes my backup tools to copy it again, which results in a lot of unnecessary data shuffling. And last but not least, I don't trust any tool to modify my RAW negatives. What's to say PM isn't making changes that will make my RAW file or the embedded metadata unreadable to some other tool? When an application changes data in a proprietary file format, there is always non-zero risk that something will get botched, which is why I stick to tools that don't modify my files.
So as much as I would love to use PM for its speed and simplicity, I can't unless there is some way to make it treat my RAW files as read-only. Is there some way to accomplish this?
Thank you.