[NTG-context] colorizing pictures

Hans Hagen j.hagen at xs4all.nl
Tue Mar 19 16:34:24 CET 2019


On 3/19/2019 4:23 PM, Henning Hraban Ramm wrote:
> Am 2019-03-19 um 13:23 schrieb Hans Hagen <j.hagen at xs4all.nl>:
> 
>> On 3/18/2019 7:45 PM, Henning Hraban Ramm wrote:
>> from one of the manuals ...
>>
>> \starttext
>>
>> \definecolor [my-blue]   [c=1,m=.38,y=0,k=.64] % pms 2965 uncoated m
>> \definecolor [my-yellow] [c=0,m=.28,y=1,k=.06] % pms  124 uncoated m
>>
>> \definespotcolor [my-blue-100]   [my-blue]   [p=1]
>> \definespotcolor [my-yellow-100] [my-yellow] [p=1]
>> \definespotcolor [my-blue-50]    [my-blue]   [p=.5]
>> \definespotcolor [my-yellow-50]  [my-yellow] [p=.5]
>>
>> \definemultitonecolor [my-mix] [my-blue=.12,my-yellow=.28] [c=.1,m=.1,y=.3,k=.1]
> 
> So it works only with toned or multitone colors and only with _some_ greyscale pictures, not with bitmaps and also not with my greyscale dodo.

It uses an indexed (256 so one byte) image ... coloring a cow is no 
option anyway as there the pdf object is an independent thing (i coul 
dprobably inject color directives if needed but that could then 
interfere with the way such a pdf stream is set up.

> I can also only use one version my-blue – if I use my-blue-100, then my-blue-50 stays grey, and if I only use my-blue-50, it’s the same tone as 100.
> 
> Something’s very fishy.
Could be but it's actually more a gimmick as we can't really mess to 
much with the internals of images (they can have masks, palettes, etc etc).

Later this year there might be other tricks on our sleeves but I'm not 
going to touch the code now.

Hans

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