From owner-freebsd-questions@FreeBSD.ORG Wed Sep 3 08:34:35 2008 Return-Path: Delivered-To: freebsd-questions@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id E33801065679 for ; Wed, 3 Sep 2008 08:34:35 +0000 (UTC) (envelope-from iwrTech@iwr.ru.ac.za) Received: from f.mail.ru.ac.za (f.mail.ru.ac.za [IPv6:2001:4200:1010::25:6]) by mx1.freebsd.org (Postfix) with ESMTP id 211B38FC1E for ; Wed, 3 Sep 2008 08:34:35 +0000 (UTC) (envelope-from iwrTech@iwr.ru.ac.za) Received: from iwr.ru.ac.za ([146.231.64.249]:51171) by f.mail.ru.ac.za with esmtp (Exim 4.69 (FreeBSD)) (envelope-from ) id 1Kanou-000PFE-Jh; Wed, 03 Sep 2008 10:34:32 +0200 Received: from iwr61.iwr.ru.ac.za ([146.231.64.161]) by iwr.ru.ac.za with esmtp (Exim 4.69 (FreeBSD)) (envelope-from ) id 1Kanou-000FZR-Iy; Wed, 03 Sep 2008 10:34:32 +0200 From: "DA Forsyth" Organization: IWR To: freebsd-questions@freebsd.org Date: Wed, 03 Sep 2008 10:34:34 +0200 MIME-Version: 1.0 Message-ID: <48BE683A.13293.2D4930EF@iwrtech.iwr.ru.ac.za> Priority: normal In-reply-to: <20080902173329.867AC106571B@hub.freebsd.org> References: <20080902173329.867AC106571B@hub.freebsd.org> X-mailer: Pegasus Mail for Windows (4.41) Content-type: text/plain; charset=US-ASCII Content-transfer-encoding: 7BIT Content-description: Mail message body X-Virus-Scanned: f.mail.ru.ac.za (146.231.129.38) Cc: freebsd@optiksecurite.com Subject: Re: How to compare 2 images from command line X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list Reply-To: iwrTech@iwr.ru.ac.za List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 03 Sep 2008 08:34:36 -0000 On 2 Sep 2008 , freebsd-questions-request@freebsd.org entreated about "freebsd-questions Digest, Vol 231, Issue 5": > > Yes, there's a huge difference between testing differences in images and > > testing differences in files. What do you mean by "...know if the > > display is working correctly."? > > > > Andrew > > I want to determine if Mplayer is working correctly. The best way to be > sure is to check if the display on the screen is changing. That's the > purpose of the screenshots. The screenshots are taken by Nagios every 5 > minutes and the new screenshot is compared with the preceding one. But, > by now, it doesn't work because every tool we try is seeing a diffence > between 2 identical images. JPG format will always be different because of the encoding/compression. I think you need to save to an uncompressed format like BMP. Maybe PNG has a mode that will work too. BMP has no info headers, just the raw data, so that won't be affected by the time of the save (at the least). -- DA Fo rsyth Network Supervisor Principal Technical Officer -- Institute for Water Research http://www.ru.ac.za/institutes/iwr/