AWARE SYSTEMS
TIFF and LibTiff Mail List Archive

Thread

2002.06.20 16:25 "Photoshop 7 TIFF Jpeg compressed.", by Bruno LEDOUX
2002.07.03 13:26 "Photometric interpretation for grey-scale JPEG", by Jon Saxton
2002.07.04 05:13 "Re: Photometric interpretation for grey-scale JPEG", by Tom Lane
2002.07.04 16:01 "Re: Photometric interpretation for grey-scale JPEG", by Jon Saxton
2002.07.04 17:40 "Re: Photometric interpretation for grey-scale JPEG", by Tom Lane
2002.07.05 00:24 "Re: Photometric interpretation for grey-scale JPEG", by Jon Saxton
2002.07.05 01:23 "Re: Photometric interpretation for grey-scale JPEG", by Tom Lane

2002.07.03 13:26 "Photometric interpretation for grey-scale JPEG", by Jon Saxton

I had a discussion on this topic recently with another member of this mailing list.

I encountered a bunch of JPEG-in-TIFF images which were encoded with a Photometric Interpretation tag set to 6 (YCrCb) and it seemed to me that this should be perfectly acceptable even though the TIFF 6.0 document says that greyscale images should be flagged as either 0 (MINISWHITE) or 1 (MINISBLACK).

As I understand matters, the luminance component of the image can be viewed as a greyscale image regardless of the weighting coefficients. In other words, it is the equivalent of an image comprising just the Y channel.

Is this correct? If so, then should 6 be an acceptable PI for grey JPEG-in-TIFF?

On consistency grounds, this actually seems more "correct" to me than the recommended values.

--
Jon Saxton <js@triton.vg> OS/2 software developer
U.S. agent for Triton Technologies International Ltd
http://www.triton.vg/