IC is even more restrictive than IB -- not only are all channels of an image stored as a single data format in the in-memory cache tiles, but in fact only a few types are allowed (I think uint8, uint16, half, and float) and anything else will be translated to one of those as the tiles are read into the cache.
> On Jul 28, 2021, at 2:23 PM, Anders Langlands <anderslangla...@gmail.com> > wrote: > > Thanks Larry, yeah my question was really about whether I need to handle the > possibility of multiple types per pixel in the Rust API (which would be > gnarly). Does the same apply for ImageCache? > > On Thu, 29 Jul 2021 at 09:05, Larry Gritz <l...@larrygritz.com > <mailto:l...@larrygritz.com>> wrote: > ImageBuf stores one data type for all channels. It's a purposeful constraint > to simplify both the internals and the use of ImageBuf. (Just imagine the > extra complexity of any ImageBufAlgo function if it had to work correctly for > any mix of channel types within the same image.) > > Upon reading a file in, it will choose the "smallest" type that can represent > all the channel types in the file (e.g., if an exr file that's a mix of float > and half, the ImageBuf will be float, but if it was all half channels, the IB > will be half). > > But an ImageBuf remembers the types in the original file it read from (this > is partly what spec() vs nativespec() does), so when you call ib->write() to > save it as a file again, it will return everything to the original types. > That way, a file -> IB -> file round trip doesn't screw up the data types of > the files. > > If you want in-memory per-channel formats, you need to manage your own > buffers and use ImageInput methods to read the truly native types (pass the > requested format as 'TypeUnknown' to mean "don't do any translation, keep the > original data types." > > > >> On Jul 28, 2021, at 1:54 PM, Anders Langlands <anderslangla...@gmail.com >> <mailto:anderslangla...@gmail.com>> wrote: >> > > >> Apologies if this is in the docs, but I haven't found a clear answer so far. >> Are images in an ImageBuf and an ImageCache stored in memory with the same >> type for each channel of a given subimage? Or might different channels have >> different types? >> >> Cheers, >> Anders > >> _______________________________________________ >> Oiio-dev mailing list >> Oiio-dev@lists.openimageio.org <mailto:Oiio-dev@lists.openimageio.org> >> http://lists.openimageio.org/listinfo.cgi/oiio-dev-openimageio.org >> <http://lists.openimageio.org/listinfo.cgi/oiio-dev-openimageio.org> > > -- > Larry Gritz > l...@larrygritz.com <mailto:l...@larrygritz.com> > > > > > _______________________________________________ > Oiio-dev mailing list > Oiio-dev@lists.openimageio.org <mailto:Oiio-dev@lists.openimageio.org> > http://lists.openimageio.org/listinfo.cgi/oiio-dev-openimageio.org > <http://lists.openimageio.org/listinfo.cgi/oiio-dev-openimageio.org> > _______________________________________________ > Oiio-dev mailing list > Oiio-dev@lists.openimageio.org > http://lists.openimageio.org/listinfo.cgi/oiio-dev-openimageio.org -- Larry Gritz l...@larrygritz.com
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