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<div dir="ltr"><div><div><div><div><div>Hi Mike,<br><br></div>From Open Printing mailing list - apparent discrepancy in <br></div>PWG Raster spec definition for "sGray".<br><br></div>Please take a look at this.<br>
<br></div>Cheers,<br></div>- Ira<br><div><div><div><div><div><div><div><div dir="ltr"><div style="display:inline"></div><div style="display:inline"></div><div style="display:inline"></div><div></div><div></div><div></div>
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<br><br><div class="gmail_quote">---------- Forwarded message ----------<br>From: <b class="gmail_sendername">James Cloos</b> <span dir="ltr"><<a href="mailto:cloos@jhcloos.com">cloos@jhcloos.com</a>></span><br>Date: Sat, May 31, 2014 at 5:30 AM<br>
Subject: [Printing-architecture] pwgtoraster vs calibrated spaces<br>To: <a href="mailto:printing-architecture@lists.linux-foundation.org">printing-architecture@lists.linux-foundation.org</a><br><br><br>I was wrong about sGray. It turns out that sGray is not defined as<br>
having the same curve as sRGB, but rather it always has gamma 2.2.<br>
<br>
The cupsraster document says srgb gamma/whitepoint, and the pwg raster<br>
doc says srgb grayscale. But everything else I've found says 2.2.<br>
And it seems a D50 illuminate.<br>
<br>
That being said, this colorspace dictionary:<br>
<br>
[ /CalGray<br>
<< /WhitePoint [ 0.96420288 1.0 0.82490540 ]<br>
/Gamma 2.2<br>
>><br>
]<br>
<br>
in stead of /DeviceGray should work for converting sGray pages to pdf.<br>
<br>
For AdobeRGB, you can use this:<br>
<br>
[ /CalRGB<br>
<< /WhitePoint [ 0.95045471 1.0 1.08905029 ]<br>
/Gamma [ 2.2 2.2 2.2 ]<br>
>><br>
endobj<br>
<br>
For sRGB, though, you'll have to embed the icc file.<br>
<br>
AFAICT, put the space in an object and specify a ref to that object<br>
where you currently specify /DeviceRGB, usw.<br>
<br>
-JimC<br>
--<br>
James Cloos <<a href="mailto:cloos@jhcloos.com">cloos@jhcloos.com</a>> OpenPGP: 0x997A9F17ED7DAEA6<br>
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