🚀 go-pugleaf

terryc wrote:
> On Fri, 23 Jan 2009 10:12:39 +0000, The Natural Philosopher wrote:
> 
> 
>> But what is HPJIS, and foomatic, and where does ghostscript come in?
> 
> AFAIK, these are old style stuff for lpr, lprng, etc. If you have cups,
> then you shouldn't need to install these.
> 
> Ghostscript does the ripping, aka converts the print commands
> into code that the printer understands. AFAIK, foomatic provides
> pre and post processing of the input/output
> 

whatevr that means..
> 
>> I suspect my problems are with ghostscript actually,
> 
> Unless it is something bleeding edge, highly nlikely. Ghostscript has been
> around for decades and has never given me trouble with watermarks, etc
> 

well it has to be whatever takes PDFs and turns them into postcript.


>> So I upgraded from
>> the latest stable debian to the bleeding edge testing sources, but it
>> still has an issue (transparent background images in PDFs do not have
>> the transparency respected)..that is something that looks like a couple
>> of days worth at the source code level would fix..but where to first be
>> sure that is the issue, and secondly identify where images are handled
>> in Ghostscript. Its HUGE.
>>
>> Anyone care to point me in the right direction?
> 
> Have you checked that the postscript code being fed into the front end
> actually has the correct Postscript in it. More likely, the application
> printing the pdf isn't creating the postscript properly.
> 

well yes, I have. In that every other PDF renderer actually sees the 
correct output, but cups cant print it.

That goes for both my home brew PDFS generated from code, and exports 
from CorelDraw.


> although pdfs are supposed to be postscript internally. Differing versions
> of postscript?

No. I am almost certain its ghostscript

The correct way to apply a transparency is to flatten the non 
transparent parts down to their pixel values, and then to flatten the 
transparent parts  to whatever is 'behind' them. This is non trivial, 
and my guess is that ghostscript simply doesn't bother, but assumes that 
the background is white, or somesuch.