AWARE SYSTEMS
TIFF and LibTiff Mail List Archive

Thread

2004.01.23 04:48 "[Tiff] How to convert MINISBLACK to PHOTOMETRIC_RGB", by Pushkar Pradhan
2004.01.23 05:15 "Re: [Tiff] How to convert MINISBLACK to PHOTOMETRIC_RGB", by Bob Friesenhahn
2004.01.23 07:39 "Re: [Tiff] How to convert MINISBLACK to PHOTOMETRIC_RGB", by Andrey Kiselev
2004.01.23 15:18 "Re: [Tiff] How to convert MINISBLACK to PHOTOMETRIC_RGB", by Bob Friesenhahn
2004.01.23 15:48 "Re: [Tiff] How to convert MINISBLACK to PHOTOMETRIC_RGB", by Frank Warmerdam
2004.01.23 15:57 "Re: [Tiff] How to convert MINISBLACK to PHOTOMETRIC_RGB", by Bob Friesenhahn
2004.01.23 16:44 "Re: [Tiff] How to convert MINISBLACK to PHOTOMETRIC_RGB", by Frank Warmerdam
2004.01.23 18:59 "RE: [Tiff] How to convert MINISBLACK to PHOTOMETRIC_RGB", by Pushkar Pradhan
2004.01.23 20:29 "Re: [Tiff] How to convert MINISBLACK to PHOTOMETRIC_RGB", by Andrey Kiselev
2004.01.23 17:16 "Re: [Tiff] How to convert MINISBLACK to PHOTOMETRIC_RGB", by Joris Van Damme
2004.01.23 17:38 "Re: [Tiff] How to convert MINISBLACK to PHOTOMETRIC_RGB", by Frank Warmerdam
2004.01.23 17:57 "Re: [Tiff] How to convert MINISBLACK to PHOTOMETRIC_RGB", by Joris Van Damme
2004.01.23 18:55 "Re: [Tiff] How to convert MINISBLACK to PHOTOMETRIC_RGB", by Frank Warmerdam
2004.01.23 19:15 "Re: [Tiff] How to convert MINISBLACK to PHOTOMETRIC_RGB", by Joris Van Damme
2004.01.23 19:19 "Re: [Tiff] How to convert MINISBLACK to PHOTOMETRIC_RGB", by Bob Friesenhahn
2004.01.23 19:24 "Re: [Tiff] How to convert MINISBLACK to PHOTOMETRIC_RGB", by Frank Warmerdam
2004.01.23 20:12 "Re: [Tiff] How to convert MINISBLACK to PHOTOMETRIC_RGB", by Chris Cox
2004.01.23 20:30 "Re: [Tiff] How to convert MINISBLACK to PHOTOMETRIC_RGB", by Bob Friesenhahn
2004.01.23 20:52 "Re: [Tiff] How to convert MINISBLACK to PHOTOMETRIC_RGB", by Chris Cox
2004.01.23 19:15 "Re: [Tiff] How to convert MINISBLACK to PHOTOMETRIC_RGB", by Bob Friesenhahn
2004.01.23 20:17 "Re: [Tiff] How to convert MINISBLACK to PHOTOMETRIC_RGB", by Andy Cave

2004.01.23 20:52 "Re: [Tiff] How to convert MINISBLACK to PHOTOMETRIC_RGB", by Chris Cox

I am by no means an authority on the TIFF specification. My interpretation of the file in question is that a sensible application should render the first band in greyscale and ignore the 2nd and 3rd since they are extra samples with no meaning attached.

Or load the 2nd and 3rd channels as alpha (not transparency) channels -- as Photoshop does.

It would be incorrect to interpret this image as RGB.

How does Photoshop treat a second alpha channel? Does it actually get used for anything?

Alpha channels are just alpha channels - they get loaded and the user can do what they want with them.

Only transparency (associated alpha) has any special meaning.

Chris