OK, I did some digging, and it's a bit of a good news / bad news situation.
Bad news: JPEG doesn't directly store the pixel aspect ratio in its metadata. Good news: JPEG does store "density" (dots per inch or cm in x and y), and so the pixel aspect ratio is implied to be ydensity/xdensity. Bad news: our JPEG reader (and writer) didn't handle xdensity and ydensity properly. (This is supposed to correspond to the standard OIIO metadata called "XResolution" and "YResolution", which are confusing names, but they are simply inherited from TIFF nomenclature.) Good news: I have a pull request (https://github.com/OpenImageIO/oiio/pull/1042) that fixes it, and also tightens up the way we handle the mutual interactions of XResolution, YResolution, and PixelAspectRatio. Once this PR is approved and merged, you'll be able to set the implied pixel aspect ratio of a JPEG file like this: oiiotool input.jpg -attrib "PixelAspectRatio" 1.1 -o nonsquare.jpg On Jan 22, 2015, at 9:46 AM, ran sariel <[email protected]> wrote: > just change the metadata > > On 01/22/2015 12:30 AM, Larry Gritz wrote: >> aspect ratio > > -- > Ran Sariel > CTO / Pipeline supervisor > The Embassy VFX Inc. > 177 West 7th Ave, 4th Floor > Vancouver, BC > Phone: (604) 696-6862 ext. 244 > > [email protected] > -- Larry Gritz [email protected] _______________________________________________ Oiio-dev mailing list [email protected] http://lists.openimageio.org/listinfo.cgi/oiio-dev-openimageio.org
