Sun Jun 18, 2017 2:52 pm
Image file formats that can carry an alpha: PNG, TIFF, OpenEXR, JPEG-2000 (not the regular jpeg, the one with the extension .jp2), Targa, DPX (not supported in all software).
I'm not as strong on video file formats. Some QT codecs can carry alpha, such as ProRes4444 and PhotoPNG. I would guess that some flavors DNxHD have alpha, also.
Bryan Ray
http://www.bryanray.name
http://www.sidefx.com