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Date: Thu, 23 Oct 2008 15:12:34 -0500 (CDT)
From: Bob Friesenhahn <bfriesen@simple.dallas.tx.us>
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On Thu, 23 Oct 2008, Jeffrey Ratcliffe wrote:

> Is there any way of telling at runtime from the command line (or with
> perlmagick) whether libjpeg is compiled for 8 or 12 bit? Or can I
> safely assume that it is 8 bit?

12 bit JPEG is very rare.  I don't know of a way to ask libtiff what 
JPEG depth it supports. If you include the libjpeg headers, then the 
define BITS_IN_JSAMPLE will be '12' if the associated libjpeg is 
compiled for 12 bits.  However, it is theoretically possible that 
libtiff was not compiled against that header or library.

Unless you are planning on making the huge effort required to support 
8/12 bit JPEG in the same application (or finish the work on David 
Gabriel's bi-modal libjpeg) I would not worry about 12 bit JPEG.

I think that 12 bit JPEG is a very good thing but since libjpeg makes 
it difficult to use, and 12-bit JPEG is quite rarely used, it is best 
left for specialized applications.

Bob
======================================
Bob Friesenhahn
bfriesen@simple.dallas.tx.us, http://www.simplesystems.org/users/bfriesen/
GraphicsMagick Maintainer,    http://www.GraphicsMagick.org/

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