<div dir="ltr"><div><div>Hi Philip,<br><br></div>there is one more important thing. For printing the file should conform to PDF/X which means PDF 1.4. It is important for colour printing, for printing in black higher minor versions of PDF are often acceptable but transparency is not allowed. If you specify colour in the \font primitive as non-transparent black, it might be optimized by the engine to grayscale. If the colour specification contains four bytes, it is RGBA, i.e. it defines transparency which is not allowed. Lookig at your samples it seeme to me that the \font command has higher priority than \color. It seems to me that the preflight is right but there are cases when Adobe Acrobat Professional is not able to fix the PDF properly, in some (but not all) cases ghostscript is more successfull (by ps2pdf14). It is better to solve the problem in the TeX source.<br><br></div>If you forget transparency and no one notices it, then it is transparent on the screen, it will be transparent on your office printer but the transparent areas will be printed as black on the offset device. That's why I double-check all included bitmap images.<br><br></div><div class="gmail_extra"><br clear="all"><div><div class="gmail_signature" data-smartmail="gmail_signature">Zdeněk Wagner<br><a href="http://ttsm.icpf.cas.cz/team/wagner.shtml" target="_blank">http://ttsm.icpf.cas.cz/team/wagner.shtml</a><br><a href="http://icebearsoft.euweb.cz" target="_blank">http://icebearsoft.euweb.cz</a></div></div>
<br><div class="gmail_quote">2016-06-27 12:06 GMT+02:00 Philip Taylor <span dir="ltr"><<a href="mailto:P.Taylor@rhul.ac.uk" target="_blank">P.Taylor@rhul.ac.uk</a>></span>:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div bgcolor="#FFFFFF" text="#000000"><span class="">
<br>
<br>
<div>David Carlisle wrote:<br>
</div>
<blockquote type="cite">
<pre>see the color package documentation
\color[cmyk]{0.1,0.2,0.3,0.4} hello
</pre>
</blockquote>
<br>
</span><span class=""><div>Zdenek Wagner wrote:<br>
</div>
<blockquote type="cite">
<pre>if you want to use the colour feature of the OpenType fonts, only RGB
is supported. The color package allows you to use both CMYK and
grayscale (both are allowed in the printing industry). You can, of
course, set the colour by promitives. You have to use both k and K for
CMYK and both g and G for grayscale (r and R are for RGB). We have a
nice article on simple graphics in CSTUG Bulletin, but only in Czech,
see <a href="http://bulletin.cstug.cz/doi.php/10.5300/2013-1/13" target="_blank">http://bulletin.cstug.cz/doi.php/10.5300/2013-1/13</a>
Zdeněk Wagner
<a href="http://ttsm.icpf.cas.cz/team/wagner.shtml" target="_blank">http://ttsm.icpf.cas.cz/team/wagner.shtml</a>
<a href="http://icebearsoft.euweb.cz" target="_blank">http://icebearsoft.euweb.cz</a></pre>
</blockquote></span>
My thanks to you both. I am beginning to realise just how complex
the world of colour is when it comes to typesetting/printing (a fact
of which I have remained in blissful ignorance until now). I am
also starting to think that the pre-flight check for "List non B/W
objects" in Adobe Acrobat 7.1 are not as reliable as one might hope
-- the behaviour does not seem to be deterministic, nor does it
appear to tally with reality : all six pages of the PDF generated
by code below are reported as "Object uses black only is not true".
But I am even more confused to discover that in XeTeX, the first
four blocks all yield visibly black-on-white text, yet only two
instances yields true black while two of the others yield RGB black
and the fifth yields RGB white -- this must indicate that I do not
understand the function of the "transparency" byte in XeTeX's font
syntax. And the sixth and final block yields RGB black despite the
call to \color [cmyk] ...<br>
<br>
<tt>\nopagenumbers<br>
<br>
</tt><tt>
</tt>
<p style="margin-top:0px;margin-bottom:0px;margin-left:0px;margin-right:0px;text-indent:0px"> </p>
<tt>
</tt>
<p style="margin-top:0px;margin-bottom:0px;margin-left:0px;margin-right:0px;text-indent:0px"><tt>
\input eplain</tt></p>
<tt>
</tt>
<p style="margin-top:0px;margin-bottom:0px;margin-left:0px;margin-right:0px;text-indent:0px"><tt>
\beginpackages</tt></p>
<tt>
</tt>
<p style="margin-top:0px;margin-bottom:0px;margin-left:0px;margin-right:0px;text-indent:0px"><tt>
\usepackage {color}</tt></p>
<tt>
</tt>
<p style="margin-top:0px;margin-bottom:0px;margin-left:0px;margin-right:0px;text-indent:0px"><tt>
\endpackages<br>
<br>
</tt></p>
<tt>
</tt>
<p style="margin-top:0px;margin-bottom:0px;margin-left:0px;margin-right:0px;text-indent:0px"> </p>
<tt>
</tt>
<p style="margin-top:0px;margin-bottom:0px;margin-left:0px;margin-right:0px;text-indent:0px"><tt> \font
\thisfont = "Arial Unicode MS"</tt></p>
<tt>
</tt>
<p style="margin-top:0px;margin-bottom:0px;margin-left:0px;margin-right:0px;text-indent:0px"><tt>
\thisfont</tt></p>
<tt>
</tt>
<p style="margin-top:0px;margin-bottom:0px;margin-left:0px;margin-right:0px;text-indent:0px"><tt> I
appear in black-on-white and am true black (0.0)</tt></p>
<tt>
</tt>
<p style="margin-top:0px;margin-bottom:0px;margin-left:0px;margin-right:0px;text-indent:0px"><tt>
\vfill \eject<br>
<br>
</tt></p>
<tt>
</tt>
<p style="margin-top:0px;margin-bottom:0px;margin-left:0px;margin-right:0px;text-indent:0px"> </p>
<tt>
</tt>
<p style="margin-top:0px;margin-bottom:0px;margin-left:0px;margin-right:0px;text-indent:0px"><tt> \font
\thisfont = "Arial Unicode MS:color=000000"</tt></p>
<tt>
</tt>
<p style="margin-top:0px;margin-bottom:0px;margin-left:0px;margin-right:0px;text-indent:0px"><tt>
\thisfont</tt></p>
<tt>
</tt>
<p style="margin-top:0px;margin-bottom:0px;margin-left:0px;margin-right:0px;text-indent:0px"><tt> I
appear in black-on-white and am RGB black (0/0/0)</tt></p>
<tt>
</tt>
<p style="margin-top:0px;margin-bottom:0px;margin-left:0px;margin-right:0px;text-indent:0px"><tt>
\vfill \eject<br>
<br>
</tt></p>
<tt>
</tt>
<p style="margin-top:0px;margin-bottom:0px;margin-left:0px;margin-right:0px;text-indent:0px"> </p>
<tt>
</tt>
<p style="margin-top:0px;margin-bottom:0px;margin-left:0px;margin-right:0px;text-indent:0px"><tt> \font
\thisfont = "Arial Unicode MS:color=FFFFFF" </tt></p>
<tt>
</tt>
<p style="margin-top:0px;margin-bottom:0px;margin-left:0px;margin-right:0px;text-indent:0px"><tt>
\thisfont</tt></p>
<tt>
</tt>
<p style="margin-top:0px;margin-bottom:0px;margin-left:0px;margin-right:0px;text-indent:0px"><tt> I
appear in black-on-white and am true black (0.0)</tt></p>
<tt>
</tt>
<p style="margin-top:0px;margin-bottom:0px;margin-left:0px;margin-right:0px;text-indent:0px"><tt>
\vfill \eject<br>
<br>
</tt></p>
<tt>
</tt>
<p style="margin-top:0px;margin-bottom:0px;margin-left:0px;margin-right:0px;text-indent:0px"> </p>
<tt>
</tt>
<p style="margin-top:0px;margin-bottom:0px;margin-left:0px;margin-right:0px;text-indent:0px"><tt> \font
\thisfont = "Arial Unicode MS:color=0000007F"</tt></p>
<tt>
</tt>
<p style="margin-top:0px;margin-bottom:0px;margin-left:0px;margin-right:0px;text-indent:0px"><tt>
\thisfont</tt></p>
<tt>
</tt>
<p style="margin-top:0px;margin-bottom:0px;margin-left:0px;margin-right:0px;text-indent:0px"><tt> I
appear in black-on-white and am RGB black (0/0/0)</tt></p>
<tt>
</tt>
<p style="margin-top:0px;margin-bottom:0px;margin-left:0px;margin-right:0px;text-indent:0px"><tt>
\vfill \eject<br>
<br>
</tt></p>
<tt>
</tt>
<p style="margin-top:0px;margin-bottom:0px;margin-left:0px;margin-right:0px;text-indent:0px"> </p>
<tt>
</tt>
<p style="margin-top:0px;margin-bottom:0px;margin-left:0px;margin-right:0px;text-indent:0px"><tt> \font
\thisfont = "Arial Unicode MS:color=FFFFFF7F"</tt></p>
<tt>
</tt>
<p style="margin-top:0px;margin-bottom:0px;margin-left:0px;margin-right:0px;text-indent:0px"><tt>
\thisfont</tt></p>
<tt>
</tt>
<p style="margin-top:0px;margin-bottom:0px;margin-left:0px;margin-right:0px;text-indent:0px"><tt> I
appear in white-on-white and am RGB white (1/1/1)</tt></p>
<tt>
</tt>
<p style="margin-top:0px;margin-bottom:0px;margin-left:0px;margin-right:0px;text-indent:0px"><tt>
\vfill \eject<br>
<br>
</tt></p>
<tt>
</tt>
<p style="margin-top:0px;margin-bottom:0px;margin-left:0px;margin-right:0px;text-indent:0px"> </p>
<tt>
</tt>
<p style="margin-top:0px;margin-bottom:0px;margin-left:0px;margin-right:0px;text-indent:0px"><tt> \font
\thisfont = "Arial Unicode MS:color=000000"</tt></p>
<tt>
</tt>
<p style="margin-top:0px;margin-bottom:0px;margin-left:0px;margin-right:0px;text-indent:0px"><tt>
\thisfont </tt><tt>\color [cmyk] {0.1, 0.2, 0.3, 0.4}</tt></p>
<tt>
</tt>
<p style="margin-top:0px;margin-bottom:0px;margin-left:0px;margin-right:0px;text-indent:0px"><tt> I
appear in black-on-white and am RGB black (0/0/0) despite the
call to \string \color \space [cmyk] ...</tt></p>
<tt>
</tt>
<p style="margin-top:0px;margin-bottom:0px;margin-left:0px;margin-right:0px;text-indent:0px"><tt>
\vfill \eject </tt></p>
<tt></tt>
<p style="margin-top:0px;margin-bottom:0px;margin-left:0px;margin-right:0px;text-indent:0px"><tt><br>
</tt></p>
<tt>
</tt>
<p style="margin-top:0px;margin-bottom:0px;margin-left:0px;margin-right:0px;text-indent:0px"> </p>
<tt>
</tt>
<p style="margin-top:0px;margin-bottom:0px;margin-left:0px;margin-right:0px;text-indent:0px"><tt> \end</tt><span class="HOEnZb"><font color="#888888"><br>
<br>
</font></span></p><span class="HOEnZb"><font color="#888888">
<div>-- <br>
<img src="cid:part4.AA3824F6.5059B400@Rhul.Ac.Uk"><br>
Philip Taylor</div>
</font></span></div>
<br><br>
<br>
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<br></blockquote></div><br></div>