Return-Path: <tiff-bounces@lists.maptools.org>
X-Original-To: info@awaresystems.be
Delivered-To: info@awaresystems.be
Received: from mx-i.b-one.net (mx-i.one.com [91.198.169.56])
	by mail9.b-one.net (Postfix) with ESMTP id 4A550400223
	for <info@awaresystems.be>; Mon, 12 Jan 2009 17:59:32 +0100 (CET)
X-Virus-Scanned: by one.com
X-Spam-Score: 0
X-Spam-Level: 
X-Spam-Status: No, score=0 tagged_above=0 required=6 tests=[none]
X-Greylist: domain auto-whitelisted by SQLgrey-1.7.4
Received: from lists.maptools.org (lists.maptools.org [65.39.174.144])
	by mx-i.b-one.net (Postfix) with ESMTP id AC95E8C2A
	for <info@awaresystems.be>; Mon, 12 Jan 2009 17:59:30 +0100 (CET)
Received: from localhost.localdomain (localhost.localdomain [127.0.0.1])
	by lists.maptools.org (Postfix) with ESMTP id B8D5F1D0C12BD;
	Mon, 12 Jan 2009 11:58:59 -0500 (EST)
Received: from exprod6og105.obsmtp.com (exprod6og105.obsmtp.com [64.18.1.189])
	by lists.maptools.org (Postfix) with ESMTP id 399331CFEAE48
	for <tiff@lists.maptools.org>; Mon, 12 Jan 2009 11:50:50 -0500 (EST)
Received: from source ([192.150.8.22]) by exprod6ob105.postini.com
	([64.18.5.12]) with SMTP
	ID DSNKSWt04fAX4bwLAHA9gmMNvIQwmqe/ioj/@postini.com;
	Mon, 12 Jan 2009 08:50:51 PST
Received: from inner-relay-1.corp.adobe.com ([153.32.1.51])
	by outbound-smtp-2.corp.adobe.com (8.12.10/8.12.10) with ESMTP id
	n0CGoXE0005076; Mon, 12 Jan 2009 08:50:34 -0800 (PST)
Received: from nahub01.corp.adobe.com (nahub01.corp.adobe.com [10.8.189.97])
	by inner-relay-1.corp.adobe.com (8.12.10/8.12.10) with ESMTP id
	n0CGoXiq000620; Mon, 12 Jan 2009 08:50:33 -0800 (PST)
Received: from nambx03.corp.adobe.com ([10.8.189.93]) by
	nahub01.corp.adobe.com ([10.8.189.97]) with mapi;
	Mon, 12 Jan 2009 08:50:32 -0800
From: Chris Cox <ccox@adobe.com>
To: myopicwatchmaker <myopicwatchmaker@gmail.com>, TIFF
	<tiff@lists.maptools.org>
Date: Mon, 12 Jan 2009 08:50:32 -0800
Thread-Topic: [Tiff] Libtiff compression ratios
Thread-Index: Acl0Vcxsumu0r5W/S9OWGtCKevthUwAgBVD1
Message-ID: <C590B4D8.7BE86%ccox@adobe.com>
In-Reply-To: <23f2496d0901111719g3061f644m52b59a684165cc7b@mail.gmail.com>
Accept-Language: en-US
Content-Language: en
X-MS-Has-Attach: 
X-MS-TNEF-Correlator: 
acceptlanguage: en-US
MIME-Version: 1.0
Subject: Re: [Tiff] Libtiff compression ratios
X-BeenThere: tiff@lists.maptools.org
X-Mailman-Version: 2.1.9
Precedence: list
List-Id: TIFF and libtiff discussion <tiff.lists.maptools.org>
List-Unsubscribe: <http://lists.maptools.org/mailman/listinfo/tiff>,
	<mailto:tiff-request@lists.maptools.org?subject=unsubscribe>
List-Archive: <http://lists.maptools.org/mailman/private/tiff>
List-Post: <mailto:tiff@lists.maptools.org>
List-Help: <mailto:tiff-request@lists.maptools.org?subject=help>
List-Subscribe: <http://lists.maptools.org/mailman/listinfo/tiff>,
	<mailto:tiff-request@lists.maptools.org?subject=subscribe>
Content-Type: text/plain; charset="us-ascii"
Content-Transfer-Encoding: 7bit
Sender: tiff-bounces@lists.maptools.org
Errors-To: tiff-bounces@lists.maptools.org


Photoshop may work on larger strips than LibTIFF.
And Photoshop does use the horizontal predictor by default with LZW and Flate compression.

Chris




On 1/11/09 5:19 PM, "myopicwatchmaker" <myopicwatchmaker@gmail.com> wrote:

Hi All,
As part of my doctoral thesis work, I produce two and a half terapixels of grayscale images a month.  As you might imagine, I am eager to minimize the storage requirements for this data.  Libtiff's support for deflate compression has served me quite well up until this point.

Recently I noticed that with identical compression settings, Adobe Photoshop CS2 achieves significantly higher compression ratios than my libtiff code--producing files that are almost 40% smaller in many cases.

A typical example: I have a 30,000x6500pixel 8-bit grayscale image which, uncompressed occupies 174Mb on disk.  Libtiff's deflate algorithm compresses this down to a 66Mb file, where Photoshop produces a 48Mb file. I save my images in ~8Mb strips, which appears to be the optimum for zip compression.

Does anyone know why libtiff might fail to match Photoshop's compression rates?  Are there any paramters in libtiff or libzip that might allow optimization for humungous images?

Thanks for any input.
Nick
_______________________________________________
Tiff mailing list: Tiff@lists.maptools.org
http://lists.maptools.org/mailman/listinfo/tiff
http://www.remotesensing.org/libtiff/
