I'm
afraid you are not understanding what a Halftone is.
I have
been involved in printing for over 20 years
I use
almost a complete PDF workflow in my shop.
You
can set a default Halftone in a PDF,
we do
it all the time from every program that creates PDFs that we
use.
This
is not about a Spot Function on objects, i'm not even sure what that
means
When
you print a PDF on a halftone device, be it a Laser-Printer or an Image-Setter
that creates film for Press
you
need a Line-Screen.
The
output-device can set the screen, or it can use the embedded one in the
PDF.
Just
look at the print dialog for Adobe Acrobat!
It has
a check box even Titled "Use Device Halftones" if this is unchecked, the
device
will
use the embedded halftone information.
Below
is code directly out of the PDf Reference
28 0 obj
<< /Type /Halftone
/HalftoneType 1
/Frequency 120
/Angle 30
/SpotFunction /CosineDot
/TransferFunction /Identity
>>
endobj
Thank you
Bill Ensley
P.S. As for the most folks that don't need/care about it, that's just naive
-----Original Message-----At 12:52 PM 3/1/2004, Bill Ensley wrote:
From: Leonard Rosenthol [mailto:[EMAIL PROTECTED]
Sent: Monday, March 01, 2004 10:34 AM
To: Bill Ensley; iText Mail Group
Subject: RE: [iText-questions] Re-Post: Line-Screen
Please refer to Adobe PDF Reference Guide
Line-Screens and Halftones are a HUGE part of PDF.I assume you are referring to the spot function which can be used to produce a line-screen LIKE result for certain object types, yes?? If so, then yes, I guess you could call it that - but it's not a full & complete "line screen" as needed in some printing processes. That's why folks who are that anal about printing control will rasterize FIRST, then adjust the raster to match the screen, and then print the raster image.
If this library is going to be the best, and I think it can be
(I'll gladly help), it should include this feature.
Sure, supporting spot functions as part of the creation for spot colors seems like a nice addition - you will need to it for all uses of spot (both raster & vector). However, honestly, most folks don't need/care about it. You'll find very few PDFs (for print) that actually have them.
Leonard
---------------------------------------------------------------------------Leonard Rosenthol <mailto:[EMAIL PROTECTED]>Chief Technical Officer <http://www.pdfsages.com>PDF Sages, Inc. 215-629-3700 (voice)215-629-0789 (fax)
