Return-Path: owner-tiff@olympiakos.com
Return-Path: <owner-tiff@olympiakos.com>
Received: from localhost (localhost [127.0.0.1])
	by at1895.spb.edu (8.12.1/8.12.1/Debian -1) with ESMTP id g0PFnZss008750
	for <dron@localhost>; Fri, 25 Jan 2002 18:50:55 +0300
Received: from eudoramail.com [209.185.123.45]
	by localhost with POP3 (fetchmail-5.9.0)
	for dron@localhost (single-drop); Fri, 25 Jan 2002 18:50:55 +0300 (MSK)
Received: from gate7.olympiakos.com ([207.176.88.85]) by shared1-mail.whowhere.com; Fri Jan 25 07:02:48 2002
Received: from localhost (daemon@localhost)
	by gate7.olympiakos.com (8.9.3/8.9.3) with SMTP id JAA10390;
	Fri, 25 Jan 2002 09:29:17 -0500
Received: by gate7.olympiakos.com (bulk_mailer v1.9); Fri, 25 Jan 2002 09:27:55 -0500
Received: (from majordom@localhost)
	by gate7.olympiakos.com (8.9.3/8.9.3) id JAA10292
	for tiff-outgoing; Fri, 25 Jan 2002 09:27:55 -0500
X-Authentication-Warning: gate7.olympiakos.com: majordom set sender to owner-tiff@olympiakos.com using -f
Received: from web12607.mail.yahoo.com (web12607.mail.yahoo.com [216.136.173.230])
	by gate7.olympiakos.com (8.9.3/8.9.3) with SMTP id JAA10289
	for <tiff@olympiakos.com>; Fri, 25 Jan 2002 09:27:52 -0500
Message-ID: <20020125142749.38099.qmail@web12607.mail.yahoo.com>
Received: from [193.203.82.162] by web12607.mail.yahoo.com via HTTP; Fri, 25 Jan 2002 15:27:49 CET
Date: Fri, 25 Jan 2002 15:27:49 +0100 (CET)
From: =?iso-8859-1?q?Thomas=20Kumlehn?= <thomaskumlehn@yahoo.de>
Subject: Re: How to interpret 16-bit GrayScale image?
To: Daniel McCoy <mccoy@pixar.com>, tiff@olympiakos.com,
   Bad Badtz <badtzbad@hotmail.com>, "Martí_Maria" <marti@littlecms.com>
In-Reply-To: <200201211723.JAA28409@moomin.pixar.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=iso-8859-1
Sender: owner-tiff@olympiakos.com
Precedence: bulk
Status: RO
Content-Length: 1002
Lines: 37

 --- Daniel McCoy <mccoy@pixar.com> schrieb: >
<marti@littlecms.com> wrote:
> ...
> When converting the OTHER way, from 8 bits UP to 16
> bits, of course, you want to MULTIPLY by 257 and 
> not 256 so that you fill in the low bits.  
> That way FF becomes FFFF instead of FF00.
> Clearly better.  No question.

I found a much faster way :
Just copy the high byte down to the low byte
00 -> 00 00
01 -> 01 01
...
FE -> FE FE
FF -> FF FF

This way, the value range is evenly filled and it's
much faster with bit ops (shift/or).

But most often need colour corr. and the like and use
LUTs anyway.

=====
kind regards,

Thomas Kumlehn
PIXEL PARTNER (R)
mobile +44 7960 384334

__________________________________________________________________

Gesendet von Yahoo! Mail - http://mail.yahoo.de
Ihre E-Mail noch individueller? - http://domains.yahoo.de

To subscribe or unsubscribe email tiff-request@olympiakos.com with subscribe
or unsubscribe in the email body.  Libtiff home page: http://www.libtiff.org

