Re: Meta-Data Import

[David Moore <dcm MIT EDU>]

On Mon, 2006-04-10 at 14:33 -0400, Warren Baird wrote:
> I must admit I'm not that familiar with XMP and IPTC headers...   If 
> they are rich enough to represent all of the metadata I need, that 
> sounds like a good solution.
> 
> Does f-spot already read this data when importing photos?
> 

I haven't downloaded the latest version of f-spot in several months, but
my understanding is that it reads XMP metadata when importing photos.

> I'm a little concerned by the possible performance implications of 
> keeping the in-image metadata as the authoritative source...  I probably 
> already have about 10k images - and that number is growing rapidly. 
> With 100k images, I suspect just checking the timestamps against a 
> database might take some time...
> 

GNOME has gamin and/or FAM which is can be used by applications to be
asynchronously notified of file alteration.  Recent kernels have support
for this so that it can done with little to no CPU overhead.  Although
I'm not certain how gracefully it handles recursive directory
monitoring.

> Ick.   I don't like this solution much.   I haven't moved to RAW yet --- 
> but I'm contemplating it.   My concern is that if anyone uses a file 
> management tool that doesn't understand whatever means is used to 
> associate the metadata file with the RAW file - you lose all of your 
> metadata...

Well, that's the whole point of using a separate file.  You might have
dsc_1234.nef and dsc_1234.xmp stored in the directory -- the former is
the RAW file and the latter is the metadata.  Since the metadata is a
plain file, it's easy to see in ordinary file management applications
and can be backed up and moved like any regular file.  And it's named
similar to the original so they always show up side by side when viewing
a directory listing -- very hard to accidentally destroy the metadata.

A centralized database cannot be backed up and moved with the images
without hard work and knowledge by the user.  Yes, some sort of XML
interchange format could be devised, but it still requires some
knowledge on the users part to do the import and export properly.

> It's been a while since I've looked at the spec of the open RAW format 
> standard --- does it support XMP or something like it?   If so, then a 
> workable solution for RAW would just be to convert everything to the 
> open format...
> 

Not sure, but there will never be a true open replacement for RAW.  RAW
is by definition "raw data" from the camera, and although there will be
open interchange formats such as DNG (which does support XMP), RAW files
will always exist because they are the true pristine data from the
camera.

-David