# [NTG-context] Rendering differences between PDF viewers

Hans Hagen pragma at wxs.nl
Tue Apr 24 14:42:29 CEST 2012

```On 20-4-2012 09:50, Peter Rolf wrote:
> Am 19.04.2012 20:25, schrieb Hans Hagen:
>> On 18-4-2012 13:12, Peter Rolf wrote:
>>
>>> I understand that there is no easy or general solution for this.
>>> But on the other hand is PNG currently the only way to use transparent
>>> bitmaps in TeX. The usage of transparent PNG is quite common, so this is
>>> a general problem that should be solved.
>>>
>>> I like your idea of automatically adding such groups, if the user
>>> declares the color space beforehand. Also no answer for the spot color
>>> problem, but as long as the user does not limit the used color spaces,
>>> things can stay as they are. Just my 2 cents.
>>
>> so first wen need to test with mixed color space documents and such
>> hacks to see what happens (as we don't want invalid documents)
>>
>
> ok. i don't expect any formal problems, only more or less ugly color
> shifts. anyhow, we will see.
>
> needs some thinking about proper examples (colored text, vector and
> pixel based graphics in RGB,CMYK,Spot)...
> i think 'draw ColorCircle(..)' is a perfect candidate for the complete
> graphic part. one page with transparency and also one page without any
> transparency (the page group shouldn't kick in). later on we can add
> some icc profiles to spice things up.
>
> i'll start to make a test document on the weekend then. if i have missed
> something important, let me know. any additional ideas are also welcome :-)

as a prelude, the next beta will have

\setupcolors[pagecolormodel=rgb] % gray rgb cmyk auto none

and issue a warning when no model is set when using transparencies

Hans

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