From mboxrd@z Thu Jan 1 00:00:00 1970 X-Msuck: nntp://news.gmane.io/gmane.comp.tex.context/69620 Path: news.gmane.org!not-for-mail From: luigi scarso Newsgroups: gmane.comp.tex.context Subject: Re: CMYK colors not as expected Date: Wed, 29 Jun 2011 08:08:52 +0200 Message-ID: References: Reply-To: mailing list for ConTeXt users NNTP-Posting-Host: lo.gmane.org Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="===============0271615555==" X-Trace: dough.gmane.org 1309327749 3731 80.91.229.12 (29 Jun 2011 06:09:09 GMT) X-Complaints-To: usenet@dough.gmane.org NNTP-Posting-Date: Wed, 29 Jun 2011 06:09:09 +0000 (UTC) To: mailing list for ConTeXt users Original-X-From: ntg-context-bounces@ntg.nl Wed Jun 29 08:09:05 2011 Return-path: Envelope-to: gctc-ntg-context-518@m.gmane.org Original-Received: from balder.ntg.nl ([195.12.62.10]) by lo.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1QbnxO-0001TW-SC for gctc-ntg-context-518@m.gmane.org; Wed, 29 Jun 2011 08:09:02 +0200 Original-Received: from localhost (localhost [127.0.0.1]) by balder.ntg.nl (Postfix) with ESMTP id CB5A2CAE19; Wed, 29 Jun 2011 08:09:01 +0200 (CEST) X-Virus-Scanned: Debian amavisd-new at balder.ntg.nl Original-Received: from balder.ntg.nl ([127.0.0.1]) by localhost (balder.ntg.nl [127.0.0.1]) (amavisd-new, port 10024) with LMTP id rJYbjri0vZAi; Wed, 29 Jun 2011 08:08:59 +0200 (CEST) Original-Received: from balder.ntg.nl (localhost [127.0.0.1]) by balder.ntg.nl (Postfix) with ESMTP id 452FECAE07; Wed, 29 Jun 2011 08:08:59 +0200 (CEST) Original-Received: from localhost (localhost [127.0.0.1]) by balder.ntg.nl (Postfix) with ESMTP id 6EB4CCAE07 for ; Wed, 29 Jun 2011 08:08:57 +0200 (CEST) X-Virus-Scanned: Debian amavisd-new at balder.ntg.nl Original-Received: from balder.ntg.nl ([127.0.0.1]) by localhost (balder.ntg.nl [127.0.0.1]) (amavisd-new, port 10024) with LMTP id HxTbiWExkkeG for ; Wed, 29 Jun 2011 08:08:55 +0200 (CEST) Original-Received: from filter3-ams.mf.surf.net (filter3-ams.mf.surf.net [192.87.102.71]) by balder.ntg.nl (Postfix) with ESMTP id 1B4EACADB8 for ; Wed, 29 Jun 2011 08:08:55 +0200 (CEST) Original-Received: from mail-pv0-f169.google.com (mail-pv0-f169.google.com [74.125.83.169]) by filter3-ams.mf.surf.net (8.14.3/8.14.3/Debian-5+lenny1) with ESMTP id p5T68r9i028756 for ; Wed, 29 Jun 2011 08:08:54 +0200 Original-Received: by pvc12 with SMTP id 12so723268pvc.14 for ; Tue, 28 Jun 2011 23:08:53 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :content-type; bh=GcVze7nc9mOPnrcukKHqCmGXhf+r0WgfSKat6Nvx9tw=; b=vSR/78TzfSxoN1+qUQmpUKSrmtYOUhJTHjKaiig2ZLhZw4QaCJ/9rhVZKSEDZlMq+0 btdtgyDsqPyNonMWd2xiOIqMbeuYNrLwtIxwRomj24DMWoav+S4hscTZ4N3AfPGOGbKY qX7DsfdJ8B+3CVxmJ8qOBLk08O88AWgnMCdig= Original-Received: by 10.68.27.130 with SMTP id t2mr651828pbg.230.1309327732994; Tue, 28 Jun 2011 23:08:52 -0700 (PDT) Original-Received: by 10.68.56.232 with HTTP; Tue, 28 Jun 2011 23:08:52 -0700 (PDT) In-Reply-To: X-Bayes-Prob: 0.0001 (Score 0, tokens from: @@RPTN) X-CanIt-Geo: ip=74.125.83.169; country=US; region=CA; city=Mountain View; postalcode=94043; latitude=37.4192; longitude=-122.0574; metrocode=807; areacode=650; http://maps.google.com/maps?q=37.4192,-122.0574&z=6 X-CanItPRO-Stream: uu:ntg-context@ntg.nl (inherits from uu:default, base:default) X-Canit-Stats-ID: 0cF1G8S9I - bd06580061e1 - 20110629 X-Scanned-By: CanIt (www . roaringpenguin . com) on 192.87.102.71 X-BeenThere: ntg-context@ntg.nl X-Mailman-Version: 2.1.12 Precedence: list List-Id: mailing list for ConTeXt users List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Original-Sender: ntg-context-bounces@ntg.nl Errors-To: ntg-context-bounces@ntg.nl Xref: news.gmane.org gmane.comp.tex.context:69620 Archived-At: --===============0271615555== Content-Type: multipart/alternative; boundary=bcaec520eb6b6b726304a6d39eb7 --bcaec520eb6b6b726304a6d39eb7 Content-Type: text/plain; charset=UTF-8 2011/6/28 Hans van der Meer > I would be pleased to get some advice from "color-knowledgeable people" on > the following matter. > > In TV-broadcasts there are usually two kinds of subtitles present: Teletext > as characters and DVB as pixels. These can be extracted and rendered with > Metapost. I have done this, but I am not very satisfied with the colors > produced. On the television screen they look bright, when rendered in > Metapost they are dull and muddy. The text is barely readable. > > As I am fairly sure I did extract the correct bits from the CLUT contained > in the stream, I wonder if I am doing something not right at the Metapost > side. In the datastream the values given are the most significant 6, 4, 4 > and 2 bits of respectively Y, Cr, Cb, T. These are scaled to the values > given to Metapost by dividing them by 255. > > In the zip one finds the program (ConTeXt MKIV) used for typesetting, an > example pixel map with clut, and the output. I would be obliged to get some > comments. > > > have you already seen http://en.wikipedia.org/wiki/YCbCr ? -- luigi --bcaec520eb6b6b726304a6d39eb7 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable

2011/6/28 Hans van der Meer <h.vandermeer@uva.nl>= ;
I would be pleased to get some advice from "color-knowledgeable people= " on the following matter.

In TV-broadcasts there are usually two kinds of subtitles present: Teletext= as characters and DVB as pixels. These can be extracted and rendered with = Metapost. I have done this, but I am not very satisfied with the colors pro= duced. On the television screen they look bright, when rendered in Metapost= they are dull and muddy. The text is barely readable.

As I am fairly sure I did extract the correct bits from the CLUT contained = in the stream, I wonder if I am doing something not right at the Metapost s= ide. In the datastream the values given are the most significant 6, 4, 4 an= d 2 bits of respectively Y, Cr, Cb, T. These are scaled to the values given= to Metapost by dividing them by 255.

In the zip one finds the program (ConTeXt MKIV) used for typesetting, an ex= ample pixel map with clut, and the output. I would be obliged to get some c= omments.


have you already seen=C2=A0
--
luigi

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