2011.02.10 17:23 "Re: [Tiff] ImageDepth tag", by Grissom, Edward

I could not find mention of the ImageDepth tag at http://www.awaresystems.be/imaging/tiff/tifftags/search.html

 Does anyone have a reference description for this tag?

 Thanks.

 --
 ed grissom
 ed.grissom@intergraph.com

 -----Original Message-----
 From: tiff-bounces@lists.maptools.org [mailto:tiff-bounces@lists.maptools.org] On Behalf Of Frank Warmerdam
 Sent: Thursday, February 10, 2011 10:49 AM
 To: tiff@lists.maptools.org
 Subject: Re: [Tiff] ImageDepth tag

 On 11-02-10 11:33 AM, John Evans wrote:
 > Hello, I was wondering what people's experiences are with the ImageDepth tag.
 > There are a few mentions of it on this mailing list if one goes back far
 > enough, but every TIFF I've seen so far (that has actually had the ImageDepth
 > tag set) has had ImageDepth trivially set to 1, such as "cramps-tile.tif".
 > Every TIFF except for one, that is. That particular TIFF was pretty simple
 > otherwise, photometric interpretation of MINISBLACK, SamplesPerPixel = 1,
 > ImageDepth = 16.
 >
 > I can see how the ImageDepth tag could be useful, i.e. just one IFD with
 > thousands of slices vs. thousands of IFDs each with just one slice. And I
 > can create TIFFs with with ImageDepth> 1 in other photometric
 > interpretations, such as RGB and YCbCr... but do people ever actually run
 > into such beasts?

 John,

 I have not encountered TIFF files with non-trivial image depth values. I
 doubt there is much client software ready for them. I'm not even convinced
 that libtiff handles them well.

 In *theory* I can see some utility for ImageDepth, but in practice I
 would prefer to just avoid promoting it's use.

 Best regards,
 --

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