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January 2004
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2004.01.23 16:44 "Re: How to convert MINISBLACK to PHOTOMETRIC_RGB", by Frank Warmerdam
Bob Friesenhahn wrote: > On Fri, 23 Jan 2004, Frank Warmerdam wrote: > > Bob Friesenhahn wrote: > > > > > How does this treat the two extra samples? Does it ignore them? > > > > I believe that GDAL treats the 3 samples as red, green and blue in the > > command shown by Andrey. > > And GraphicsMagick will only extract the primary gray channel. > > > PS. I don't think the Imagine generated TIFF file is so odd. In the > > satellite imaging community it is common for us to use MINISBLACK for > > multispectral tiff files. The only odd part, in my mind, is the use of > > the unspecified ExtraSamples tag. When I see multi-sample MINISBLACK > > TIFF files I assume that each sample should be treated as MINISBLACK with > > no obvious pre-set RGB sample combinations. > > Right. MINISBLACK is pretty ordinary. The intent/meaning of the extra > samples is undefined and may be proprietary. Perhaps they could be > some sort of mask, or overlays which can be enabled/disabled in > viewing software. Bob, They are not masks. They are just extra MINISBLACK samples/bands/channels. I have worked on the Imagine GeoTIFF code at times, and I don't think the ExtraSamples stuff was meant to imply the extra bands were anything special. I will agree that including the ExtraSamples <undefined> tag muddies the water quite a bit. Best regards, -- ---------------------------------------+-------------------------------------- I set the clouds in motion - turn up | Frank Warmerdam, warmerdam@pobox.com light and sound - activate the windows | http://pobox.com/~warmerdam and watch the world go round - Rush | Geospatial Programmer for Rent