Received: from mailgate007.isp.belgacom.be (mailgate007.isp.belgacom.be [195.238.5.213])
	by maildelivery016.isp.belgacom.be (Postfix) with ESMTP id 6977A558069
	for <joris.at.lebbeke@skynet.be>; Wed,  4 Jul 2007 19:57:36 +0200 (CEST)
Received: from r153.dmsolutions.ca (HELO duke.maptools.org) ([209.217.116.153])
  by in.mx.skynet.be with ESMTP; 04 Jul 2007 19:57:35 +0200
Received: from duke.maptools.org (duke.maptools.org [127.0.0.1])
	by duke.maptools.org (8.12.11/8.12.10) with ESMTP id l64Ho6TO023450;
	Wed, 4 Jul 2007 13:50:15 -0400
Received: from smtpout.mac.com (smtpout.mac.com [17.250.248.185])
	by duke.maptools.org (8.12.11/8.12.10) with ESMTP id l64Ho3cr023446
	for <tiff@lists.maptools.org>; Wed, 4 Jul 2007 13:50:04 -0400
Received: from mac.com (smtpin08-en2 [10.13.10.153])
	by smtpout.mac.com (Xserve/smtpout15/MantshX 4.0) with ESMTP id
	l64Ho3rh021941
	for <tiff@lists.maptools.org>; Wed, 4 Jul 2007 10:50:03 -0700 (PDT)
Received: from [10.0.1.8] (c-24-18-225-212.hsd1.mn.comcast.net [24.18.225.212])
	(authenticated bits=0)
	by mac.com (Xserve/smtpin08/MantshX 4.0) with ESMTP id l64Ho166029282
	for <tiff@lists.maptools.org>; Wed, 4 Jul 2007 10:50:02 -0700 (PDT)
Mime-Version: 1.0
Message-Id: <p0624081ec2b189c30c42@[10.0.1.8]>
In-Reply-To: <03cf01c7be60$7dc4b610$da60fea9@EKAT>
References: <03cf01c7be60$7dc4b610$da60fea9@EKAT>
Date: Wed, 4 Jul 2007 10:49:58 -0700
To: tiff@lists.maptools.org
From: Stephen Carlsen <sc42business@mac.com>
Subject: Re: [Tiff] 16-Bit-Per-Channel Lossless Compression
Content-Type: text/plain; charset="us-ascii"
X-Brightmail-Tracker: AAAAAA==
X-Brightmail-scanned: yes
X-BeenThere: tiff@lists.maptools.org
X-Mailman-Version: 2.1.4
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>
Sender: tiff-bounces@lists.maptools.org
Errors-To: tiff-bounces@lists.maptools.org
X-UIDL: 000000000023ceae.00002526
X-MSP-STORE: Wed, 04 Jul 2007 19:57:36 +0200
Status:   

Hi Andy,

Yup, I've actually done quite a bit of testing, and running LZW with predictor tends to compress 16-bit digital camera photographs very little, or even not at all. The problem, of course, is that the low order bits tend to look a lot like noise.

I can post some sample files if you like. On one of my images from my Canon XTi, exported from DNG to uncompressed TIFF (using Lightroom), the uncompressed size is 57.7 MB, but is 68.8 MB with LZW (plus predictor) compression.

Flate tended to generally do worse than LZW, and be a lot slower, in my testing.

Stephen


At 6:26 PM +0100 7/4/07, Andy Cave wrote:
>PS With LZW, have you tried with prediction enabled? That should improve the compression ratio on 16 bit ints.
>
>----- Original Message ----- From: "Andy Cave" <andy.cave@hamillroad.com>
>To: <tiff@lists.maptools.org>; "Stephen Carlsen" <sc42business@mac.com>
>Sent: Wednesday, July 04, 2007 6:24 PM
>Subject: Re: [Tiff] 16-Bit-Per-Channel Lossless Compression
>
>>Hi Stephen,
>>
>>Are you saying that LZW or Flate do not get 2:1? Have you tried either of these? What ratios do you get?
>>
>>Do you have some example files for testing with?
>>
>>I think if you can compress and write to disk faster than you can write, compression is always worth it. Sure storage space is getting larger and faster, but then CPUs are getting more and more cores, which can nicely do compression in parallel.
>>
>>Andy.
>>
>>----- Original Message ----- From: "Stephen Carlsen" <sc42business@mac.com>
>>To: <tiff@lists.maptools.org>
>>Sent: Wednesday, July 04, 2007 6:13 PM
>>Subject: [Tiff] 16-Bit-Per-Channel Lossless Compression
>>
>>>It seems to me that none of the lossless compression schemes commonly used in TIFF are very effective at compressing 16 bit or 32 bit data. And, with technologies such as Camera Raw gaining in popularity rapidly, there's a lot more 16 bit data out there.
>>>
>>>If we can come up with a simple approach that gives us on the order of 2:1 compression of 16 bit photographs, is this useful, or are storage space and bandwidth now so inexpensive that we don't care any more?
>>>_______________________________________________
>>>Tiff mailing list: Tiff@lists.maptools.org
>>>http://lists.maptools.org/mailman/listinfo/tiff
>>>http://www.remotesensing.org/libtiff/

_______________________________________________
Tiff mailing list: Tiff@lists.maptools.org
http://lists.maptools.org/mailman/listinfo/tiff
http://www.remotesensing.org/libtiff/
