Before I give a full answer... 

C++ or Python? Or command line?

ImageInput or ImageBuf or ImageCache/TextureSystem? 

On August 6, 2017 11:34:12 AM PDT, Kenny Carruthers <> 
>I’m using OpenImage IO and extracting the metadata from an image using
>the extra_attribs() method on ImageSpec. Is there a way to tell
>OpenImage IO that I’m only going to be accessing the metadata and that
>no image loading or decoding needs to occur? 
>In particular, the RawInput class, which uses libraw, calls unpack()
>which is a very slow method because of the RAW decoding that needs to
>take place. However, that call to unpack() is being made at the start
>of the ImageInput::open() method and there doesn’t appear to be any
>flag one can set to disable that. Further down that method, it calls
>through to read_tiff_metadata() which is really all that one needs if
>they are only interested in the metadata.
>If I disable libraw support in OpenImageIO, then OIIO defaults to
>opening a Nikon NEF file with another plugin that only loads the
>metadata since it can’t load the raw data. That code path is very fast
>but I don’t know how to trigger it if raw support is built-in (or how
>to tell the raw plugin itself). 
>Thank you. 
>Kenny Carruthers
>macOS Developer
>Corduroy Code Inc,
>Oiio-dev mailing list

Larry Gritz
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