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2019.01.12 17:25 "tiffcp altering image contents (in contrast to what the manual says)?", by <lists@binarus.de>
2019.01.12 19:09 "Re: tiffcp altering image contents (in contrast to what the manual says)?", by Bob Friesenhahn
2019.01.12 21:07 "Re: Tiff Digest, Vol 3, Issue 3", by Richard Nolde
2019.01.13 15:41 "Re: tiffcp altering image contents (in contrast to what the manual says)?", by <lists@binarus.de>
2019.01.13 19:24 "Re: tiffcp altering image contents (in contrast to what the manual says)?", by Bob Friesenhahn
2019.01.13 17:04 "Re: tiffcp altering image contents (in contrast to what the manual says)?", by <lists@binarus.de>
2019.01.13 18:31 "Re: tiffcp altering image contents (in contrast to what the manual says)?", by <lists@binarus.de>
2019.01.13 19:17 "Re: tiffcp altering image contents (in contrast to what the manual says)?", by Bob Friesenhahn
2019.01.13 21:58 "Re: tiffcp altering image contents (in contrast to what the manual says)?", by <lists@binarus.de>

2019.01.13 19:17 "Re: tiffcp altering image contents (in contrast to what the manual says)?", by Bob Friesenhahn

On Sun, 13 Jan 2019, Binarus wrote:
>
> "C:\Program Files\GraphicsMagick-1.3.25-Q16\gm.exe" convert a.tif b.tif
> -compress jpeg -quality 90 1.tif
>
> If I got you right, GraphicsMagick probably applies the problematic 
> OJPEG compression when executing the command above. We will 
> investigate if we can change that. In the meantime, if our 
> investigations don't lead to anything, could you eventually give a 
> hint regarding an alternative procedure for that first step?

GraphicsMagick uses libtiff to write TIFF so it will never output 
OJPEG compression.  However, since February 7, 2015, GraphicsMagick 
uses YCbCr encoding when JPEG compression is requested for an RGB 
image because the resulting file is much smaller.  This might be a 
factor.

By the way, my own email to you was also bounced due a complaint about 
SPF records but my mail server offers one (unlike the one that Richard 
unfortunately uses) and so your bounce is the first one I have ever 
seen complaining about SFP records.

Bob
-- 
Bob Friesenhahn
bfriesen@simple.dallas.tx.us, http://www.simplesystems.org/users/bfriesen/
GraphicsMagick Maintainer,    http://www.GraphicsMagick.org/
Public Key,     http://www.simplesystems.org/users/bfriesen/public-key.txt
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