[Therion] Plan gridline colour changes unpredictably

[Bruce Mutton]

Thanks Martin

Highlights the dangers of absorbing a language by osmosis.  A false sense of understanding!

I’ll try that out and see how it works.

 

Out of interest I went back over old maps to check the colour of my gridlines.  Until a few weeks ago I only ever used the default rgb colour model, and even now I only specify rgb, but occasionally force Therion to convert by specifying a cmyk colour model.  I found that I actually got a random section of the two gridline output colours over previous years.  My excuse for not picking it as a Therion behaviour is that I routinely use a number of pdf viewers and printers.  They all present line thicknesses and colours slightly differently. Especially Sumatra pdf compared to most others.

 

Bruce

 

 

From: Therion <therion-bounces at speleo.sk> On Behalf Of Martin Budaj
Sent: Wednesday, 11 August 2021 07:23
To: List for Therion users <therion at speleo.sk>
Subject: Re: [Therion] Plan gridline colour changes unpredictably

 

Hi,

 

0.5white doesn't work in CMYK properly (it's equivalent to 0.5*(0,0,0,0) = (0,0,0,0) = white)

0.1black doesn't work in RGB (it's 0.1*(0,0,0) = (0,0,0) = black)

 

So your formula produces 50% gray in RGB and 10% gray in CMYK. No idea why you got 10% gray in some RGB setups, some test data would be needed.

 

To get 10% grey colour you need to use 0.1[white,black] which works in all RGB, CMYK and Grayscale.

 

Cheers

Martin 

 

 

On Tue, Aug 10, 2021 at 11:29 AM Bruce Mutton <bruce at tomo.co.nz <mailto:bruce at tomo.co.nz> > wrote:

Curious

 

I have in my layout some metapost code to redefine the plan gridlines, used without apparent problem for perhaps 10 years.  It includes a colour specification…

 

withcolor 0.1black+0.5white;

 

Mostly they come out like this, very light grey.  This example is exported using colour-model cmyk, but most of the time using colour-model rgb it looks exactly the same, in my current project (only variables are colour map-fg, some map previews on or off and the colour model).



 

For some reason, in my current project, if I use colour-model rgb for a particular output variant, I get a much darker gridline, as below.  Other variants with rgb, the colour of the gridline matches the first example.



 

Any hints as to why the difference?

I might have expected this to occur with the new cmyk colour model, but it does not.

So far it has only happened with in a single specific case when using the rgb colour model.  I’ll watch for more cases…

Bruce

 

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