From: luigi scarso <luigi.scarso@gmail.com>
To: mailing list for ConTeXt users <ntg-context@ntg.nl>
Subject: Re: CMYK colors not as expected
Date: Wed, 29 Jun 2011 08:08:52 +0200 [thread overview]
Message-ID: <BANLkTik9N=t8m1bdi7BzXBbbhN2o84WQwQ@mail.gmail.com> (raw)
In-Reply-To: <F882FA36-B82D-4F5F-9E65-34D4151964EE@uva.nl>
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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
> 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
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next prev parent reply other threads:[~2011-06-29 6:08 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-06-28 12:06 Hans van der Meer
2011-06-29 6:08 ` luigi scarso [this message]
2011-06-29 13:59 ` Taco Hoekwater
2011-06-29 14:10 ` Taco Hoekwater
2011-06-29 8:10 ` Hans Hagen
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