Transparency - Alpha Channels?

[Evan Larson]

Hello,

I am working on a method for creating presentations that essentially
mimics overlays or layers. What I mean is instead of going to the next
slide I want the background to remain and additional information, images
specifically, to appear on top of the background.

Currently here is what I have tried. Print to a postscript driver from
AutoCAD to create an EPS file. Bring it into Photoshop and save it to a
TIFF or PNG. Typically these files will have a white background so when
I bring them into PPT 2000 I select the white color as transparent.
This works but I have not been happy with the resulting clarity. The
images tend to be fuzzy along the transparency lines. Perhaps this is
the best method and I just need to work on my images.

Second I tried to use Alpha channels in TIFF files. Granted the only
knowledge I have on this is from the FAQ site but I did not get it to
work. I saved the file from Photoshop as suggested and all I get is a
black or white background no transparency. Obviously doing something
wrong here. Is this the best or at least a good way to accomplish what
I am trying to do? If so I will keep trying if not please point me in
the right direction.

Thanks,

Evan Larson

[TAJ Simmons]

The fuzzy edge around the image....

Ideally the background color of the bitmap (that you make transparent in
powerpoint) should match the overall colour of your background in
powerpoint. This gives the best results. If the background of your bitmap is
white and your powerpoint background is blue. This will give naff results.
If your background of your bitmap is blue and the powerpoint background is
blue, this will give excellento results

There was a good post in this newsgroup about alpha channels.
Summing it up by saying what is black will disapear in powerpoint ...or was
it the other way around....:)

cheers
TAJ

Evan Larson <ela...@gltarchitects.com> wrote in message
news:3A78606B...@gltarchitects.com...

[Echo S]

Evan, I think that if it's AutoCAD drawings you're trying to make
transparent, you might be better off using CorelDraw rather than
PhotoShop.

Anyway,
When you're in PhotoShop, you need to
1. select the background (using the wand is often an easy way, depending
on the image)
2. invert the selection (select/Inverse) to select the CAD objects/lines
on your image
3. and then use the button on the channel palette to make the selection
a channel ("save selection as channel").

Your selection (which, if you inverted as described above, consists of
your lines) will show up black in the 4th layer in the channel palette.
The background will show up as black and should be transparent when you
insert into PPT. Basically you select what you don't want to be masked.
And make sure that channel layer isn't visible (no "eye" icon) in the
channels palette. The TIF files won't come into PPT if it is.

Make sure when you "Save a copy as TIF," you haven't checked the "don't
save with Alpha Channels" box.

Echo

[Evan Larson]

TAJ,

You are likely right about that, the problem I have is that I am trying
to insert images over other non uniform colored images so there is no
good way to pick a matching color. I could however try for a neutral
color that would be less noticeable.

I will give it a try thanks,
Evan

[Evan Larson]

Echo,

I will give it a try. We have CorelDraw and that might be a better
method as you suggest. I have always had problems with getting the pen
settings correct when I bring drawings into Corel but likely I just need
to learn how.

I will try the steps you outline for the Alpha channels also.

Thanks,
Evan

[Steve Rindsberg]

Since you're starting with a vector format (ACAD) why go through all the
hassle of converting to bitmaps and then having to deal with the backgrounds
that are always part of that game?

ACAD will make WMFs ... I'd give that a try.

--
Steve Rindsberg, PowerPoint MVP
Got a PowerPoint wish/suggestion/beef?
Email msw...@microsoft.com with PowerPoint in the subject line

PPT FAQ - http://www.rdpslides.com/pptfaq
RnR PPTools - http://www.rdpslides.com/pptools
ZAP! for service bureaus - http://www.rdpslides.com/zap

Evan Larson <ela...@gltarchitects.com> wrote in message
news:3A78606B...@gltarchitects.com...

[Evan Larson]

Steve,

I am following up on your suggestion. I am having difficulty getting an
AutoCAD file out to WMF with an applied pen map.

That is my problem however... I believe I can set up a plotter as a wmf
device to do this since standard wmfout command does not apply the pen
colors and weights.

Thanks for the help.

Evan

[Steve Rindsberg]

Hi, Evan. Glad it makes sense to you, 'cause if you'd asked any more
detailed questions ... well ... let's just say that you'd have been
surprised to see just how fast a CAD-challenged 50-year-old guy can run (at
least in cyberspace). <g>

All I know is that I worked with a fellow on converting hundreds of CAD
drawings, ultimately to PDF, and he seemed to get the best results by
oomphing out WMFs. I think he did a little touchup in Corel Draw afterward,
fwiw.

--
Steve Rindsberg, PowerPoint MVP
Got a PowerPoint wish/suggestion/beef?
Email msw...@microsoft.com with PowerPoint in the subject line

PPT FAQ - http://www.rdpslides.com/pptfaq
RnR PPTools - http://www.rdpslides.com/pptools
ZAP! for service bureaus - http://www.rdpslides.com/zap

Evan Larson <ela...@gltarchitects.com> wrote in message
news:3A79DE04...@gltarchitects.com...