2006.09.27 06:13 "Re: [Tiff] Status of ISO JBIG and CIELAB JPEG support", by Graeme Gill
Photoshop doesn't support ITULAB.
Photoshop only supports CIELAB and ICCLAB encodings in TIFF.
One of the reasons I hadn't tried adding ITULAB support to my color conversion tool (Argyll/cctiff - see http://www.argyllcms.com/doc/cctiff.html) is the lack of suitable sample files, whereas it was possible to check my LAB TIFF files against Photoshop.
I wasn't attempting JPEG in TIFF Lab though.