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Eric,

I believe Photoshop is adjusting sample levels for color correction. Try
turning off all color conrrection and conversion during import.

If you wish, I'll be glad to generate a histogram using my program
(ThumbsPlus), with a guarantee that no pixels are adjusted, and email it to
you; just send me your gradient image.

Kind regards,
Phillip Crews
Cerious Software Inc.
http://www.thumbsplus.com

At 01:39 PM 7/16/99 , Eric B. Middlecamp wrote:
>Ok, here goes.. I am running on a Power Mac 8100/100 under MacOS 8.1, I am
>compiling under Codewarrior IDE 2.1, displaying the images in Adobe Photoshop
>5.0, producing the histogram in Photoshop with full data sampling (histogram 
>not
>from cache), and I am using a Mac-compiled version of the old libtiff
>"tiff-v3.4beta028," although I have compared the code for libtiff version
>"tiff-v3.4beta037" and not found any major differences.
>
>As an update, I just ran a modified version of "tiffinfo," it verified
that the
>image I have matches what Niles got when he ran it; the problem must be
related
>to the image readers, namely Photoshop. I am also writing some code which
reads
>TIFFs, though, and I have gotten some strange results there as well. Is it
>possible that I am using a valid, but uncommon/problemmatic, set of tags?


AWARE [SYSTEMS]		Imaging expertise for the Delphi developer
		TIFF and LibTiff Mailing List Archive
	LibTiff Mailing List TIFF and LibTiff Mailing List Archive July 1999 Previous Thread Next Thread Previous by Thread Next by Thread Previous by Date Next by Date Contact The TIFF Mailing List Homepage This list is run by Frank Warmerdam Archive maintained by AWare Systems	Thread 1999.07.15 23:47 "RGB Gradient Code, adapted from Andreas Neumann", by Eric B Middlecamp 1999.07.16 06:23 "Re: RGB Gradient Code, adapted from Andreas Neumann", by Niles Ritter 1999.07.16 16:17 "Re: RGB Gradient Code, adapted from Andreas Neumann", by Daniel Mccoy 1999.07.16 17:39 "Re: RGB Gradient Code, adapted from Andreas Neumann", by Eric B Middlecamp 1999.07.16 20:04 "Re: RGB Gradient Code, adapted from Andreas Neumann", by Phillip Crews 1999.07.16 16:08 "Re: RGB Gradient Code, adapted from Andreas Neumann", by Eric B Middlecamp 1999.07.16 20:04 "Re: RGB Gradient Code, adapted from Andreas Neumann", by Phillip Crews Eric, I believe Photoshop is adjusting sample levels for color correction. Try turning off all color conrrection and conversion during import. If you wish, I'll be glad to generate a histogram using my program (ThumbsPlus), with a guarantee that no pixels are adjusted, and email it to you; just send me your gradient image. Kind regards, Phillip Crews Cerious Software Inc. http://www.thumbsplus.com At 01:39 PM 7/16/99 , Eric B. Middlecamp wrote: >Ok, here goes.. I am running on a Power Mac 8100/100 under MacOS 8.1, I am >compiling under Codewarrior IDE 2.1, displaying the images in Adobe Photoshop >5.0, producing the histogram in Photoshop with full data sampling (histogram >not >from cache), and I am using a Mac-compiled version of the old libtiff >"tiff-v3.4beta028," although I have compared the code for libtiff version >"tiff-v3.4beta037" and not found any major differences. > >As an update, I just ran a modified version of "tiffinfo," it verified that the >image I have matches what Niles got when he ran it; the problem must be related >to the image readers, namely Photoshop. I am also writing some code which reads >TIFFs, though, and I have gotten some strange results there as well. Is it >possible that I am using a valid, but uncommon/problemmatic, set of tags?

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1999.07.16 20:04 "Re: RGB Gradient Code, adapted from Andreas Neumann", by Phillip Crews