From: Henning Hraban Ramm <texml@fiee.net>
To: mailing list for ConTeXt users <ntg-context@ntg.nl>
Subject: Re: color question
Date: Mon, 24 Aug 2020 09:19:02 +0200 [thread overview]
Message-ID: <D47F13B9-BF68-48CA-9F11-DA2070886C10@fiee.net> (raw)
In-Reply-To: <0f13548e-d33c-31e5-ce86-43e0e230781c@gmail.com>
> Am 24.08.2020 um 01:15 schrieb jbf <roma83537@gmail.com>:
>
> I have a very basic question about color use that someone will be able to answer easily. The background to the question is that (i) I am completely new to this scene of commercially[offset] print-ready material as distinct from what is required on screen (ii) I am using Mk IV (iii) I need spot colors set up for cmyk, and for now I need shades between black and white (e.g. light gray) for a simple design feature.
>
> My question is this: is the use of color keywords sufficient? Or in other words, have predefined color names like lighgray already been defined in, say cmyk terms behind the scenes, or must I instead \definecolor[lightgray][c=10,m=7,y=5,k=0], (or perhaps \definespotcolor with those dimensions, or do I need both)?
First: Color parts use decimal numbers from 0 to 1.
Even if some color names are predefined, you should define your grays yourself – either as shades of black only or maybe with a bit of cyan. Grays in more (process) colors are unstable and might get a tint (color cast) you don’t want. (Of course you could use other colors than cyan for some tinting, depending on your work.)
E.g. I often \definecolor[deepblack][c=.3,k=1] for black areas; the cyan portion evens out some irregularities in print.
Because I don’t trust ConTeXt’s (or my) color setup, I also \definecolor[cmykblack][k=1] to avoid “RGB black”. (But \setupcolor[cmyk=yes,rgb=no,overprint=yes] should handle that already.)
If you want to use grays as spot colors (e.g. Pantone) you must define them as such – but usually you don’t want (to pay for) more than one spot color. Spot gray makes sense if you have big areas of that color, since 100% spot color looks better than any percent rastered black.
See also:
https://wiki.contextgarden.net/Color
https://wiki.contextgarden.net/Spot_Colors
Hraban (printing engineer)
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next prev parent reply other threads:[~2020-08-24 7:19 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-23 23:15 jbf
2020-08-24 7:19 ` Henning Hraban Ramm [this message]
-- strict thread matches above, loose matches on Subject: below --
2006-10-10 11:52 Alan Bowen
2006-10-10 16:30 ` gnwiii
2006-10-12 13:04 ` Alan Bowen
2006-10-10 16:44 ` Henning Hraban Ramm
2002-05-23 4:03 Denis B. Roegel
2002-05-27 20:21 ` Hans Hagen
2002-05-27 21:02 ` Hans Hagen
1999-06-01 21:37 Color question David Arnold
1999-06-02 7:34 ` Hans Hagen
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