From mboxrd@z Thu Jan 1 00:00:00 1970 X-Msuck: nntp://news.gmane.io/gmane.comp.tex.context/15840 Path: main.gmane.org!not-for-mail From: "George N. White III" Newsgroups: gmane.comp.tex.context Subject: Re: Downsampling images in pdfTeX Date: Tue, 27 Jul 2004 14:47:04 -0300 Organization: Bedford Institute of Oceanography Sender: ntg-context-bounces@ntg.nl Message-ID: References: <001101c473ee$6e1cac00$fcb359d5@DJCPX90J> Reply-To: mailing list for ConTeXt users NNTP-Posting-Host: deer.gmane.org Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed X-Trace: sea.gmane.org 1090950487 25768 80.91.224.253 (27 Jul 2004 17:48:07 GMT) X-Complaints-To: usenet@sea.gmane.org NNTP-Posting-Date: Tue, 27 Jul 2004 17:48:07 +0000 (UTC) Original-X-From: ntg-context-bounces@ntg.nl Tue Jul 27 19:47:50 2004 Return-path: Original-Received: from ronja.vet.uu.nl ([131.211.172.88] helo=ronja.ntg.nl) by deer.gmane.org with esmtp (Exim 3.35 #1 (Debian)) id 1BpW3I-0007Oh-00 for ; Tue, 27 Jul 2004 19:47:48 +0200 Original-Received: from localhost (localhost.localdomain [127.0.0.1]) by ronja.ntg.nl (Postfix) with ESMTP id 0096912783; Tue, 27 Jul 2004 19:47:44 +0200 (CEST) Original-Received: from ronja.ntg.nl ([127.0.0.1]) by localhost (ronja.vet.uu.nl [127.0.0.1]) (amavisd-new, port 10024) with LMTP id 12534-04; Tue, 27 Jul 2004 19:47:41 +0200 (CEST) Original-Received: from ronja.vet.uu.nl (localhost.localdomain [127.0.0.1]) by ronja.ntg.nl (Postfix) with ESMTP id 0649512772; Tue, 27 Jul 2004 19:47:41 +0200 (CEST) Original-Received: from localhost (localhost.localdomain [127.0.0.1]) by ronja.ntg.nl (Postfix) with ESMTP id C160912772 for ; Tue, 27 Jul 2004 19:47:39 +0200 (CEST) Original-Received: from ronja.ntg.nl ([127.0.0.1]) by localhost (ronja.vet.uu.nl [127.0.0.1]) (amavisd-new, port 10024) with LMTP id 12461-04 for ; Tue, 27 Jul 2004 19:47:39 +0200 (CEST) Original-Received: from bionet.bio.dfo.ca (unknown [142.176.61.190]) by ronja.ntg.nl (Postfix) with ESMTP id 257E71276D for ; Tue, 27 Jul 2004 19:47:39 +0200 (CEST) Original-Received: from montigo.bio.dfo.ca ([142.2.20.184]) by bionet.bio.dfo.ca (PMDF V5.2-32 #39490) with ESMTP id <0I1I00M5WUPRLL@bionet.bio.dfo.ca> for ntg-context@ntg.nl; Tue, 27 Jul 2004 14:46:40 -0300 (ADT) In-reply-to: <001101c473ee$6e1cac00$fcb359d5@DJCPX90J> X-X-Sender: gwhite@montigo.bio.dfo.ca Original-To: mats.broberg@arsimprimispress.com, mailing list for ConTeXt users X-Virus-Scanned: by amavisd-new at ntg.nl X-BeenThere: ntg-context@ntg.nl X-Mailman-Version: 2.1.5 Precedence: list List-Id: mailing list for ConTeXt users List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: ntg-context-bounces@ntg.nl X-Virus-Scanned: by amavisd-new at ntg.nl Xref: main.gmane.org gmane.comp.tex.context:15840 X-Report-Spam: http://spam.gmane.org/gmane.comp.tex.context:15840 On Tue, 27 Jul 2004, Mats Broberg wrote: >> From: ntg-context-bounces@ntg.nl >> [mailto:ntg-context-bounces@ntg.nl] On Behalf Of George N. White III > >> As a general principle, it makes no sense for pdftex to >> provide image manipulation capabilities. Such capabilities >> are useful to a much wider >> audience than the users of pdftex, so there are lots of tools >> to do image resampling and format conversions. All that >> pdftex should do is support inclusion of pdf. The limited >> support for including png images is a convenience, but if you >> are being careful you would want to make pdf images. >> >> -- >> George N. White III >> Head of St. Margarets Bay, Nova Scotia, Canada > > Having checked the pdfTeX documentation, doesn't the internal parameter > \pdfcompresslevel deal with this? The documentation says: > > "compress level This integer parameter specifies the level of text and > in-line graphics compression. pdfTEX uses zip compression as provided by > zlib. A value of 0 means no compression, 1 means fastest, 9 means best, > 2..8 means something in between. Just set this value to 9, unless there > is a good reason to do otherwise - 0 is great for testing macros that > use \pdfliteral." The compression this parameter controls is quite different. Without compression (e.g., \pdfcompresslevel=0) a PDF file consists of almost readable text. Even images can be stored in an ASCII encoding. Setting a non-zero value for \pdfcompresslevel applies a lossless compression algorithm to objects in the pdf file. For images that will be displayed only at low resolution it may be useful to downsample the original image to reduce the size. For example you might have a 2 inch by 2 inch image scanned at 400 dpi. This image would have 800x800 pixels. For screen display you might prefer to have a 200x200 pixel image (or 100 dpi for 2 inches). Downsampling refers to the process of reducing an 800x800 pixel image to 200x200 pixels. ways to reduce image size (lossy compression, colorspace changes, even converting certain images to line art). Some tools to generate PDF include methods to downsample images. In particular, people who have been using tex-->dvipsone-->distiller and are now using just pdftex encounter problems with much larger pdf file sizes and excessive load times until they resize the input images. -- George N. White III Head of St. Margarets Bay, Nova Scotia, Canada