[XeTeX] \font "<platform font>":color=FFFFFF produces black, not white glyphs \font "<platform font>":color=FFFFFF produces black, not white glyphs, re-visited

[Ross Moore]

Hi Phil,

On 26 May 2020, at 5:12 pm, Philip Taylor <P.Taylor at Hellenic-Institute.Uk<mailto:P.Taylor at Hellenic-Institute.Uk>> wrote:

Ross Moore wrote:

I’m sorry, but this just doesn’t make any sense to me — but see further below.

No, the fourth couplet is TT, where T is "Transparency".  Unfortunately , it is a misnomer, since 00 = completely transparent and FE is almost opaque, which is why I spoke of "opacity" rather than transparency.  Unfortunately FF is not opaque when preceded by FFFFFF, because the driver treats FFFFFF [FF] specially.

As I said, it didn’t make sense to me.  :-)
Thanks for the clarification, and sorry for my added noise.


First it is important to realise that both flattening and conversion to CMKY will take place (the document is for digital printing).  When flattening takes place, RGB FFFFFF text will completely obscure the ground, and after conversion to CMYK there will then be no ink where the text occurs.  Unfortunately as things are at the moment, there will be 1/256 bleed-through of the ground because the RGB white was not perfectly opaque.

"knockout", tho' interesting, should not be needed.  The example earlier sent shews that one can get very close to 100% white (and of course there are no white inks involved) but not to 100% and this is what I would like to achieve (and which should, IMHO, be achievable).  Were it not for the fact that the driver treats FFFFFF and FFFFFFFF specially, there would be no problem at all in achieving my aim.

It looks like Akira has done what you wanted, so the exercise was a success. :-)


** Phil.

Cheers.
Stay safe.

Ross


Dr Ross Moore
Department of Mathematics and Statistics
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Macquarie University, NSW 2109, Australia
T: +61 2 9850 8955  |  F: +61 2 9850 8114
M:+61 407 288 255  |  E: ross.moore at mq.edu.au<mailto:ross.moore at mq.edu.au>
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