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Plugin to do math/arithmatic on metadata fields

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May 9, 2015
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  1. Windows 10

I found myself with a stange problem. In need to decrease the numeric portion of file name in a large number of images by a value of 1. In other words IMG1234.jpg needs to become IMG1233.jpg. As the LR plugin API does not suppoort file name manipulation in plugin's it seems that one can use Jfriedl's "write Data Field" plug in (in bog-o-goodies" collection) to copy the numeric portion of the file name to another field such as Headline. But now I need a tool that can take the value in Headline (e.g. 1234) and subtract 1 from it after which I can use the "Headline" token in LR's file rename template builder to update the actual file name.

What I'm missing is the tool to do that arithmatic on the Headline tool so if someone can point me to such a thing, I'd be grateful. I though Lightroom Solutions' "search & replace" might do it, but I don't see how to do math in that tool (maybe just looking in wrong place).

Thanks -- Dan
You can use the magic LUA token:

{LUA=return FilenameNumber - 1}

I haven't tested this, so as with all programming, there's a strong likelihood of a bug :->
Are you trying to rename a series of files (e.g. IMG1234-IMG1334) to ( IMG1233-IMG1333)? If they are in sequence you can rename from any starting value (i.e.IMG1233) and increment the rest by one.

If you don’t have a long series, it is probably just as easily to renamed the few images manually. If you did this manually, then you would like be done by now.

Sent from my iPad using Tapatalk
To compliment Cletus remarks above.

Many people do not realise you can modify an individual filename using the metadata field for "File Name".

Just put your cursor into the section of the existing field name you wish to edit. Do not change the file type.

Very useful for individual file names or a small number of filenames.

I use this regularly to put meaningful filenames on exported images I send to people via email, etc.

Gnits: Thanks - I am familiar with renaming a single file in the metadata panel as well as using a file rename template,

Cleetus: the images needing the rename are not in an unbroken numeric sequence. There are gaps

John: thanks. I'll take a look at Jeffery's blog and give the LUA code a try.

Thanks all -- Dan
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