[gs-devel] ps2pdf and size of pdf files

Ray Johnston ray.johnston at artifex.com
Sat Feb 28 20:30:00 PST 2004

Giulio Orsero wrote:

> On Fri, 27 Feb 2004 23:11:36 -0800, Ray Johnston <ray.johnston at artifex.com>
> wrote:
>>Why do you need to use the GPL version? The AFPL version if OK to use
>>for any use as long as you aren't selling a product or otherwise making
>>money from the AFPL Ghostscript. 
> Say a small business says to me "we have a linux box and want to produce pdf
> files from some text files, we use  some_linux_distro as os".
> I see the ghostscript version installed is the GPL one and is an old
> version. I thought that I cannot install the AFPL on their system since I
> would be "distributing" it (and they pay for my time working for them), but
> I had the impression that I could upgrade their GPL version with a new one;
> if this is not correct please tell me and I'll tell them they have to
> upgrade GPL or installing AFPL ghostscript by themselves.
> Also, I have some linux systems I installed for others and they have GPL gs,
> and I have the same issues (I thought it was ok to upgrade the existing GPL
> gs installed, but not to install the AFPL).

I've forwarded this issue on to those that handle our legal
interpretation of the GPL Ghostscript.

>>Note that we interpret/enforce the GPL
>>so that if you build a product that invokes Ghostscript (whether linked
>>or via the OS 'system') that your product MUST also conform to the GPL
> I think you interpret the GPL different from other people.

While it isn't "my" interpretation (I hope to get clarification /
correction from those in contact with legal experts), I think
that our interpretation is similar to that of the MySQL folks.

> Samba is GPL but is used in many commercial products and it seems it's legal
> to do so. I thought this was ok because it's legal for a commercial product
> to "use/invoke" a GPL product, but not to link to it or use its source
> (unless they release source of the product). So you think that commercial
> unices using samba are violating GPL unless they asked permission to the
> samba team?
> There are many wireless access point now that are using linux internally;
> all the worrying on the lkml was about getting them to release source for
> modifications they made to linux and busybox, not for them to release source
> of their proprietary utilities that use linux/busybox.
> However, this is just to understand your opinion about GPL, my real issue is
> the one about upgrading a GPL ghostscript that came with the linux distro to
> a newer version.

As above, I'm not a legal expert, but it seems that if you are only upgrading
a GPL version ghostscriptto a new version, and *IF* the previous used was
valid under the license, then the upgrade is not the issue.

>>This was something that was improved just before 8.14. We added code to
>>recognize Image Resources and use the same Image Resource (PDF object)
>>whenever the image data was the same.
> So, am I right saying that using postscript "form" has never and will never
> have an impact on the pdf size? That is, before the code you added near 8.14
> ps "form" was "executed" before converting to pdf and image included
> multiple times, and now "form" is still "executed" but image is included
> just once?

Correct. The 'pdfwrite' device doesn't have any special knowledge of
"forms". This is because the Ghostscript 'pdfwrite' device is a gs
device (as defined in the gxdevcli.h interface) and can actually work
with other front end (non PS) interpreters that call the graphics

> So, using ps "form" to call a single eps file multiple times (small ps input
> file) or including the same eps multiple times (large ps input file) has no
> effect on the pdf final size?

I'm not sure what you are saying here. With the newer GS, multipe images
that are the same will be 'reduced' to a single Image Resource in the
PDF. THis is done by comparison of the image data. Forms that consist
of EPS derived graphics (strokes, fills, shows, etc.) are not reduced
to images, so are not subject to recognition across multiple pages.
Note that the bulk of large PDF data is image data, *NOT* graphics
data such as fill, stroke or show.

Let's continue to explore the best approach for you and your


Ray Johnston
Director of Engineering                          Tel: (714) 484-0376
Artifex Software Inc.                            Fax: (714) 220-1022

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