Anti-alias graphic using transparency?

[L_A_R...@adobeforums.com]

I have a question concerning anti-aliasing a graphic. I’m currently using Photoshop CS2 running on Windows XP.

I have a graphic that I want to use with backgrounds of different solid colors and even the occasional multi-colored background. I want to smooth out the jaggies of the graphic in such a way that the smoothed graphic can be placed on a separate layer and the desired background can be inserted on a layer below.

I can successfully import an anti-aliased graphic IF I import the graphic and its background at the same time. But then the anti-aliased graphic is suitable for use only with that particular color background. I would like to eliminate this extra step if possible.

Suppose the graphic were black on a white background. The anti-alias pixels might be 75% gray, 50% gray, and 25% gray. Conceptually, it doesn’t seem like it should be all that difficult for the anti-alias pixels to be black at 75% transparency, black at 50% transparency, and black at 25% transparency. Then, in theory, wouldn’t this type of transparency anti-aliasing work for any color background placed underneath it? Is this possible in Photoshop CS2? If not, is it possible in a later version (might be a good reason to upgrade)?

I’ve done some searching on the ’net without results. A few sites mention the possibility of doing this with PNG files but didn’t explain HOW to do it. I’ve been using Photoshop for several years but only for processing photos. No previous graphics experience, so I need step-by-step instructions.

Many thanks.

[J_Ma...@adobeforums.com]

Make your graphic anti-aliased on a clear background (checkerboard in PS). Then use save for web to save PNG24 with transparency.

[Apex]

It sounds like you might want to bring your image into Photoshop and
apply a layer mask. Use the mask to isolate your image and allow the
new background layer to show through. I'm using CS3 (Windows) now, but
I believe that CS2 was the same. You will need to put in the time and
effort to paint around your selection, but once you master it, you'll
be able to overlay the masked layer on any photo or color background
that you want. If the image is not too intricate, you might want to
use the polygon lasso tool with 1 pixel feather to select areas that
you can fill. Check out this site for a step-by-step process.
http://photoshoptips.net/2006/07/25/layer-masks/.

Be sure that you don't merge the layers (foreground with background)
or at least keep a copy of your masked layer for future background
changes. That would be frustrating to have to do your masking again.

Happy masking!

[L_A_R...@adobeforums.com]

Sounds good, but I need some hand-holding.

I'm not creating the graphic in Photoshop. It's already created, and I'm pasting it into the document.

When I paste a graphic into a Photoshop document, it appears on a new layer anti-aliased on a white background. I don't know how to control the characteristics of a layer that hasn't been created yet to make it transparent (i.e. the layer that is created when I paste the graphic into the file). If I try to merge the layer containing the graphic with a clear background (as you say, checkerboard in PS), the graphic appears anti-aliased in white on a transparent background.

So, how do I paste my graphic into a Photoshop document "anti-aliased on a clear background"?

Thanks.

[Myle...@adobeforums.com]

What graphic and what source program? what you are experiencing may actually be a limitation in the originator app, not PS....

Mylenium

[J_Ma...@adobeforums.com]

You might try the Alphaworks filter:

<http://www.adobeforums.com/webx/.3bc34571>

[Gernot_...@adobeforums.com]

Anti-aliasing means: create artificial pixels
at edges. These have colors somewhere between
the 'main image' and the 'background'.
These pixels have interpolated colors.
If the background is transparent, then such an
interpolation doesn't exist. Because a trans-
parent background doesn't have a color.

Best regards --Gernot Hoffmann