beamer transparent image

[Guldo K]

Is it possible to include a trasparent image into a beamer presentation?
I'd like to include a png image that is partly transparent.
In the beamer documentation:
"currently only pgf offers the ability to include images that are partly
transparent."
but I can't understand how.
Simply writing:
\pgfimage{image}
would include an image with a white background.
I tried \setbeamercolor{background canvas}{bg=}, but I think it's not
the right option (if there's one).
As a background, I have an image, not a solid color, so I can't fill the
transparent layer of the png with it.

Any hint?

[Piet van Oostrum]

GK> Is it possible to include a trasparent image into a beamer presentation?
GK> I'd like to include a png image that is partly transparent.

Have a look at http://png2pdf.sourceforge.net/usage.html

[Guldo K]

Post by Piet van Oostrum

GK> Is it possible to include a trasparent image into a beamer presentation?
GK> I'd like to include a png image that is partly transparent.

Have a look at http://png2pdf.sourceforge.net/usage.html

Thanks for the info :)
Anyway... I still can't do it. :(
I've compiled and installed dklibs and png2pdf, and I've used it like this:
png2pdf -a image.png image.pdf
to keep the transparency.
Unfortunately, also this pdf image, as I insert it into the beamer file
and compile using pdflatex, still shows a white background.
What's wrong??!

Thank you.

[Jellby]

Post by Guldo K
Unfortunately, also this pdf image, as I insert it into the beamer file
and compile using pdflatex, still shows a white background.
What's wrong??!

Are you sure that's the white from the image and not the paper white?

[Guldo K]

Post by Jellby

Post by Guldo K
Unfortunately, also this pdf image, as I insert it into the beamer file
and compile using pdflatex, still shows a white background.
What's wrong??!

Are you sure that's the white from the image and not the paper white?

Let me explain it.
Perhaps I just can't understand what "transparency" stands for.
My situation is: I have a frame with a background image that covers the
whole frame. Inside this frame, I want to put another, little, image. In
this little image, there are 2 parts: one is colored, the other one is
transparent, so that I can see what lies beneath it.
So, I'd like to see the part of the little image that is colored, and I
want the transparent part of the image to be invisible, letting me see
the background image that lies beneath it.

Can I do it?!?

Thanks.

[Giuliano D'Ammando]

Post by Guldo K
Is it possible to include a trasparent image into a beamer presentation?
I'd like to include a png image that is partly transparent.
"currently only pgf offers the ability to include images that are partly
transparent."
but I can't understand how.
\pgfimage{image}
would include an image with a white background.
I tried \setbeamercolor{background canvas}{bg=}, but I think it's not
the right option (if there's one).
As a background, I have an image, not a solid color, so I can't fill the
transparent layer of the png with it.
Any hint?

Take a look at:
http://us.share.geocities.com/kijoo2000/beamer_guide.pdf

[Guldo K]

Post by Giuliano D'Ammando
http://us.share.geocities.com/kijoo2000/beamer_guide.pdf

Thank you!
That's really nice :)

bye

[Aditya Mahajan]

<--- On May 12, Guldo K wrote --->

Post by Guldo K
Is it possible to include a trasparent image into a beamer presentation?
I'd like to include a png image that is partly transparent.
"currently only pgf offers the ability to include images that are partly
transparent."
but I can't understand how.

Have a look at documentation of pgf. Basically you need to specify an
image mask while declaring an image.


HTH,
Aditya

[Guldo K]

Post by Aditya Mahajan
<--- On May 12, Guldo K wrote --->

Post by Guldo K
Is it possible to include a trasparent image into a beamer presentation?
I'd like to include a png image that is partly transparent.
"currently only pgf offers the ability to include images that are
partly transparent."
but I can't understand how.

Have a look at documentation of pgf. Basically you need to specify an
image mask while declaring an image.

Thank you for your suggestion, but I can't understand.
AFAICS, png2pdf has a "-i" option that takes no argument and converts
the alpha channel from the PNG file into a PDF image mask.
I've tried many combos of options for png2pdf, but I can't get what I
want. I want the transparent area of the image to be invisible, letting
me see the background image lying beneath it.
There's no such example in the documentation of png2pdf. All the
examples use a solid color for the background.

Thanks.

[Aditya Mahajan]

<--- On May 14, Guldo K wrote --->

Post by Guldo K

Post by Aditya Mahajan
<--- On May 12, Guldo K wrote --->

Post by Guldo K
Is it possible to include a trasparent image into a beamer presentation?
I'd like to include a png image that is partly transparent.
"currently only pgf offers the ability to include images that are partly
transparent."
but I can't understand how.

Have a look at documentation of pgf. Basically you need to specify an image
mask while declaring an image.

Thank you for your suggestion, but I can't understand.
AFAICS, png2pdf has a "-i" option that takes no argument and converts the

[snip]

I was talking about the pgf documentation. pgf is a latex package,
have a look at the documentation at

http://www.ctan.org/tex-archive/graphics/pgf/pgfuserguide.pdf

specifically section 2.8. It specifes how to declare an image mask
and how to use it to get transparency.

[Guldo K]

Post by Aditya Mahajan
<--- On May 14, Guldo K wrote --->

Post by Aditya Mahajan
<--- On May 12, Guldo K wrote --->

Post by Guldo K
Is it possible to include a trasparent image into a beamer
presentation?

[snip]
I was talking about the pgf documentation. pgf is a latex package, have
a look at the documentation at
http://www.ctan.org/tex-archive/graphics/pgf/pgfuserguide.pdf
specifically section 2.8. It specifes how to declare an image mask and
how to use it to get transparency.

Thank you very much. I'm fine, now.
(since I realized that xpdf does not support masking...)

bye

[Dirk Krause]

Guldo K <***@no_spam.it> wrote in news:YLbhe.97067$***@twister2.libero.it:

...

Post by Guldo K
I've tried many combos of options for png2pdf, but I can't get what I
want. I want the transparent area of the image to be invisible,
letting me see the background image lying beneath it.
There's no such example in the documentation of png2pdf. All the
examples use a solid color for the background.
Thanks.

Hi Guldo,
section 4.4.3 in png2pdf.pdf uses a color gradient as page background.
Did you use

\usepackage{graphicx}
...
\includegraphics{image.pdf}

to include the image? Or some other mechanism?
The statement "currently only pgf offers the ability to include
images that are partly transparent." is wrong.
All examples in png2pdf.pdf use the graphicx package and the
includegraphics instruction, you should try these mechanisms too.
Note: You must not omit the file name suffix ".pdf" in the
includegraphics instruction. If it is omitted, the PNG file is
used instead of the PDF file.
To convert the PNG to PDF you should prefer the -a option, not
the -i option. The -i option produces an image mask which is
a dual decision (draw pixel or do not draw pixel). The -a
option allows partial transparency too.


I have just made a little test using the following example:

\documentclass{beamer}
\mode<presentation>
{
\usetheme{Madrid}
\setbeamercovered{transparent}
}
\usepackage[german]{babel}
\usepackage[latin1]{inputenc}
\usepackage[T1]{fontenc}
\usepackage{ifpdf}
\usepackage{graphicx}
\usepackage{color}
\ifpdf
\hypersetup{%
pdfpagemode=FullScreen,
pdfpagetransition={Wipe /Di 0 /D 0.5}
}
\fi
\title[Beamer and png2pdf]{Using png2pdf with the beamer class}
\author[Krause]{D.~Krause}
\subject{png2pdf}
\begin{document}
\beamertemplateshadingbackground{yellow!50}{magenta!50}
\begin{frame}
\frametitle{Image over transient background}
\includegraphics{stefan_255_rgba.pdf}%
\end{frame}
\end{document}

The stefan_255_rgba.pdf file was produced from
Loading Image...
by

png2pdf -a -n stefan_255_rgba.png stefan_255_rgba.pdf

Regards,

Dirk