How to export hi-res bitmaps from PPT in order to render semitransparent fills in PDF

[Thilo Ernst]

Hi folks,

Just to save you all some trouble:

Acrobat distiller, even recent versions of it, is unable to render
semi-transparent fills correctly. The PDF format supports transparency
from version 1.4 (Acrobat 5) on, but Distiller generates PDF using
PostScript as an intermediate format and transparency is unknown to PS.

A good way to convert a PPT figure containg transparent objects into a
..pdf is generating a bitmap first (thus enforcing transparency flattening),
inserting this bitmap into a new PPT or Word document, and then invoking Distiller.

Of course for this to have an acceptable look, the bitmap should have as
high a resolution as possible.

Now Powerpoint (at least the version I use) does export bitmaps, but offers
no way of explicitly adjusting the resolution of the image.
I just found out that PPT uses the page size to determine the resolution
of the image. The program seems to assume some fixed dpi value to do this.

So simply increase your page size to insane values in "File-> Page Setup",
use "Save as ... GIF" or something along these lines and voila,
you get huge bitmaps consuming vast amounts of disk space but
looking real nice when converted to PDF and printed.

In case you need a bitmap format not supported by PPT, I recommend
using IrfanView (www.irfanview.com). It supports tons of formats,
does some manipulations and, best of all, accepts drag-and-drop of
graphics objects from Powerpoint (thanks to my lovely wife for this
hint . In this case, the PPT page size is significant as well,
and the drag-and-drop should start from the single-slide view,
not the slides overview. The viewing Zoom selected in PPT does not
influence the size of the generated bitmap though.


HTH,

TE

 

[Steve Rindsberg]

Acrobat distiller, even recent versions of it, is unable to render

semi-transparent fills correctly. The PDF format supports transparency
from version 1.4 (Acrobat 5) on, but Distiller generates PDF using
PostScript as an intermediate format and transparency is unknown to PS.

A nice, succinct description of the problem. Adobe likes to blame MS for this, MS
likes to blame Adobe. If they'd cooperate with one another, it'd have been fixed
long ago.

Your workarounds are also good ones, but there's a way that's easier, and that works
better in some cases.

Select the transparent shape and any shapes it covers.
Choose Edit, Copy or press Ctrl+C
Choose Edit, Paste Special and choose PNG

To increase the resolution of the pasted bitmap, you'll want to increase the size of
the shapes before you copy them. This won't work well with text - you'd also need to
increase the font size proportionally. A nuisance. Obviously, this technique won't
work in all cases, but where it does, it'll save the trouble of exporting images.

There are also several commercial addins that let you export slides at higher
resolutions w/o having to change page size. We have one at http://www.pptools.com

 

[Ute Simon]

Hi Thilo,

Acrobat distiller, even recent versions of it, is unable to render
semi-transparent fills correctly. [...]

Thanks for that description, and thanks for blaming Adobe for the problem
;-) I had the problem of a PDF file with terrible (semi-transparent) logos
just on Friday. Now I know it was not my (or PowerPoint's) fault.

Select the transparent shape and any shapes it covers.
Choose Edit, Copy or press Ctrl+C
Choose Edit, Paste Special and choose PNG

And thanks, Steve, for this workaround. I knew the Paste Special method to
re-insert images, but I did not think of grouping my logo with its
background (a rectangle filled with a gradient in my case). I'll try that as
soon as I am back in office on Monday!

Kind regards,
Ute

P.S.: Thilo, I notice you're from Germany, too. Do you know the monthly
German PowerPoint newsletter of www.ppt-user.de? It might be worth a look
for you.

 

[Steve Rindsberg]

Thanks for that description, and thanks for blaming Adobe for the problem

;-) I had the problem of a PDF file with terrible (semi-transparent) logos
just on Friday. Now I know it was not my (or PowerPoint's) fault.

I'll let you off innocent but not PowerPoint. The Postscript it makes when it
tries to print semi-transparent shapes is bloated and braindead. It makes the
PS and resulting PDF very slow to display and ensures that it'll look like the
dog ate, then regurgitated it if it's not displayed at *just* the right
magnification (and how likely is that?)

 

[Ute Simon]

I'll let you off innocent but not PowerPoint. The Postscript it makes

when it
tries to print semi-transparent shapes is bloated and braindead. It makes
the
PS and resulting PDF very slow to display and ensures that it'll look like
the
dog ate, then regurgitated it if it's not displayed at *just* the right
magnification (and how likely is that?)

I thought, quality of PS was dependant on printer drivers (because its
mostly a printing format) and thus a problem of Adobe Acrobat, which does a
print-to-file-job here?

Kind regards,
Ute

 

[Steve Rindsberg]

I thought, quality of PS was dependant on printer drivers (because its

mostly a printing format)

To some extent, but if the airport's to the north of your town and you tell the
driver to go to the center of the city and drive round and round and round
until you both get dizzy, and finally to go south, it's not really the driver's
fault if you miss your flight. ;-)

That's partly what happens here. PowerPoint tells the driver to do stupid
stuff, the driver does. Stupid PS results.

and thus a problem of Adobe Acrobat, which does a
print-to-file-job here?

Acrobat (the program) doesn't. The Adobe PDF driver does.

Here's the thing:

PDF can support transparency.
PostScript cannot.
If your method of making PDF involves printing to PostScript, then transparency
is out (and that's how most applications make PDF). Since Adobe hasn't really
provided alternative mechanisms, their claims for PDF support of transparency
are a little thin. "It's there but you can't get there from here." Oh.
Thanks. ;-)

 

[Ute Simon]

Steve, your examples are great! ;-)) Now I understand what's going on.

Thanks a lot,
Ute