The present and future of post production business and technology | Philip Hodgetts

Archive for June 5th, 2009



I think there’s a sixth type of metadata

When Dan Green interviewed me earlier in the week for Workflow Junkies, in part about the different types of metadata we’ve identified, Dan commented that he thought we’d get to “seven or eight” (from memory). I politely agreed but didn’t think there were going to be that many. I should have known better.

The “iPhoto disaster of May 09” is actually turning out to be good for my thinking! In earlier versions, iPhoto created a copy of the image whenever any adjustments were made. The original was stored, which explains why my iPhoto folder was almost twice the size of my actual library as reported in iPhoto. iPhoto 09 (and maybe 08, I skipped a version) does things a little differently.

When I changed images while the processor was under load, the image came up in its original form and then – a second or so later – all the corrections I’d made would be applied. It was obvious that the original image was never changed. All my color balance, brightness, contrast and even touch up settings were being stored as metadata, not “real changes”.

The original image (or “essence” in the AAF/MXF world) is untouched but there is metadata as to how it should be displayed. Including, as I said, metadata on correcting every image blemish. (The touch up tool must be a CoreImage filter as well, who knew?)

So, I’m thinking this is a different type of metadata than the five types of metadata previously identified. My first instinct was to call this Presentation Metadata – information on how to present the raw image. Greg (my partner) argued strongly that it should be Aesthetic Metadata because decisions on how to present an image or clip or scene, but I was uncomfortable with the term. I was uncomfortable because there are instances of this type of metadata that are compulsory, rather than aesthetic.

Specifically, I was thinking about Raw images (like those from most digital cameras, including RED). Raw images really need a Color Lookup Table (CLUT) before they’re viewable at all. A raw Raw file is very unappealing to view. Since not all of this type of metadata is aesthetic I didn’t feel the title was a good fit.

Ultimately, after some discussion – yes, we really spend our evenings discussing metadata while the TV program we were nominally watching was in pause – we thought that Transform Metadata was the right name.

Specifically not “Transformative” Metadata, which would appear to be more grammatically correct, because Transformative has, to me, a connotation of the transform being completed, like when a color look is “baked” into the files, say after processing in Apple’s Color or out of Avid Symphony. Transform Metadata does not change the essence or create new essence media: the original is untouched and Transfomed on presentation.

Right now we’re a long way from being able to do all color correction, reframing and digital processing in real time as metadata on moving images as iPhoto does for still images, but in a very real sense an editing Project file is really Transform Metadata to be applied to the source media (a.k.a essence).

This is very true in the case of Apple’s Motion. A Motion project is simply an XML file with the metadata as to how the images should be processed. But there’s something “magic” going on because, if you take that project file and change the suffix to .mov, it will open and play in any application that plays QuickTime movies. (This is how the Project file gets used in FCP as a Clip.) The QuickTime engine does its best to interpret the project file and render it on playback. A Motion Project file is Transform Metadata. (FWIW there is a Motion QuickTime Component installed that does the work of interpreting the Motion Project as a movie. Likewise a LiveType QuickTime Component does the same for that application’s Transform Metadata, a.k.a. project file!)

I think Dan might be right – there could well be seven or eight distinct types of metadata. It will be interesting to discover what they are.

June 2009
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