Yes, you can. All you have to do is save a selection in the image before saving the Targa; saved selections are alphas. Apparently these are either exported or interpreted automatically in the proper Targa format (e.g., Alpha 1), no matter what name you choose when you save the selection.
Testing suggests this fails if you try to save more than one alpha with the file; be sure to save only one.
That help?
Richard Lynch
The CMYK should go all go together as long as you don’t have just one channel selected. The alpha channel won’t, but you can copy and paste the alpha channel to a new layer in the first document, drag and drop all the layers together into your new document, load the selection by cmd. clicking the layer thumbnail, and save as a new alpha channel.
Or just drag the Alpha into the new document holding down Shift. It will appear in the Channels palette.
IF that is what’s wanted.
The new CS2 non-layer selection behavior is what has changed – broken a few features.
thanks everyone.
Katie, your suggestions seem to be the closest to what I need.
Here are the specifics.
I have several images of jewelry with drop shadows and an alpha channel that masks the jewelry from the drop shadow. My client would like me to layout all the images on one document. Easy nuff. But he also wants me to save the alpha channels (that masks the jewelry from the shadow) as one channel to indicate the spot varnish. He also wants me to have one layer with all the shadows on it. I don’t exactly see the point since the alpha channel will keep the shadow from being varnished. But this is how he NEEDS to have it.
This is so hard to explain w/o showing you what I’m talking about. But THANKS everyone for trying to help out!
Creating an alpha channel is really only for sharp edged selections? What do you do with the channel after you created it? Is it just to save a selection? Then what? Open it again and use the magic wand to get a selection?
What are you actually supposed to do with an alpha channel once you make it? It seems you can’t do much. I thought it was supposed to act like a mask but it doesn’t seem to do anything.
Thanks
an alpha channel has 256 levels of gray like any other channel in an 8bit file.
their use in Photoshop is more or less as you surmise, as a way to keep saved selections.
also they may be used by other applications (such a QuarkXpress) as a way to mask.
Thanks,
so if I had an alpha channel in photoshop, I can do one of two things?:
1. Use the magic wand to reselect a simple unfeathered selection (make changes to selection etc.)?
2. Send the alpha channel with a file which allows QuarkXpress to mask off an area ? (do they have to do much to use it as a mask?
Thanks
You can do a lot more than two things. You don’t need to use the Magic Wand to select from a Channel – just use Selection > Load Selection.
Ok, I see how it retains the nuances of black, gray, white, masking. Thanks ! How is an alpha channel used in Quark?
If I sent a file to a publisher or something with an alpha channel as a mask, how does that publisher utelize it in Quark?
Thank
Channels are saved selections. They are incredibly useful in many instances and can be widely manipulated. If you can find a copy of Photoshop Channel Chops it would be well worth your while to buy it and read it. The book is old but most of it is still relevant today. It can give you a good idea of just what Photoshop is all about.
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http://www.amazon.com/Photoshop-Channel-Chops-David-Biedny/d p/1562057235>
if you need to soften the edges, gaussian blur the mask to whatever degree you require in your adjustment layers
this can be used for both comping and colour correction
Also, some of the filters like the lighting filter will let you use an alpha channel. This can do some nice beveling effects. You aren’t limited to hard edged masks.
Robert
