Hello everyone, I'm struggling recently with optimizing inspection/preview of our multi-raster *.exr images. They can reach, as you know, 50-100MB on disk, what makes them really hard to work with.
My first idea was to save in *.exr yet another raster, i.e. special version of beauty-pass, saved in 8bit -- which was obviously silly. I'm mentioning this, because not only EXR doesn't support 8bit channels, but even if it does, it seems like channels are compressed&stored together, so you can't really get one channel without reading them all. In tests with oiio (and HDK for comparison) I got pretty much the same results whenever reading all data from multi-channel file or reading single channel from that file... unless file doesn't use any compression, which obviously adds extra boost, but it's not an option I'm afraid. Unfortunately my second idea which was to save a proxy as a multi-image failed also, since oiio (OpenEXR?) doesn't seem to support (?) this feature. Does it come with stereo support in OpenEXR 1.7? I'm not sure how this would work, but I image loading lightweight (ideally 8bit) second image from the file, would be much faster than dealing with all deep channels. Finally I found a preview image attribute in a Exr header... I'm suspicious, as I don't want to store tiny thumbnail, but rather full_res/half_res version of the beauty pass. So my main question is if oiio supports preview image (can't find any mention in docs nor mail-list about it), or maybe I should use an attribute in ImageSpec? Also do you see problematic to save in a header something like 4x1280x720 unsigned integers? Sorry for a long post, and thank you for any comments (and for OIIO in a first place!) -- skk. _______________________________________________ Oiio-dev mailing list [email protected] http://lists.openimageio.org/listinfo.cgi/oiio-dev-openimageio.org
