Re: CSS overprinting

On Jul 31, 2014, at 01:59, Rik Cabanier <cabanier@gmail.com> wrote:

> On Wed, Jul 30, 2014 at 3:34 PM, Lea Verou <lea@verou.me> wrote:
> Resurrecting this thread as no resolution has been reached, to mention that AntennaHouse also has its own proprietary syntax for overprinting [1]
> 
> A device dependent feature such as overprinting doesn't belong in CSS.
> Prepress workflows have the necessary logic to deal with automatically create overprinted colors depending on the colors, content used and transparency effects.

Like it has already been mentioned in the thread, overprinting cannot always be determined algorithmically, and even when it could, it would be risky to assume that this is the intent in many cases.
Transparency has little to do with overprinting. For example, can you do [1][2] with alpha transparency (or anything else, really)? 
This is why every native app for print work has an overprint option (InDesign [3], Illustrator [4], etc), and the most popular print formatters have proprietary syntax for it (Prince [5], AntennaHouse [6]). Do we want CSS to be able to compete with DTP apps or not? Cause I thought that being able to do serious print work with CSS *is* one of our goals, non?

~ Lea

[1]: http://blog.spoongraphics.co.uk/articles/how-to-overprint-colors-to-create-cool-print-effects
[2]: http://blog.spoongraphics.co.uk/articles/showcase-of-designs-made-with-cool-overprint-effects
[3]: http://helpx.adobe.com/indesign/using/overprinting.html
[4]: http://help.adobe.com/en_US/illustrator/cs/using/WS714a382cdf7d304e7e07d0100196cbc5f-6495a.html
[5]: http://www.princexml.com/doc/9.0/color/
[6]: http://antennahouse.com/xslfo/extension.htm#axf.overprint