What is Alpha Channel?

Hi, I'd like to know what an Alpha Channel is.

What can it do? Thanks...

Im not going to be a smart a$$ about this, but if you read the manual that came with your cd, it should explain somewhat of what channels are.

Don't even try, they prob. don't have a manual, otherwise he would have looked. He prob. didn't pay for it.

Originally posted by mattboy_slim
Don't even try, they prob. don't have a manual, otherwise he would have looked. He prob. didn't pay for it.

What do u mean mattboy_slim? Are u talking to me?

If u are, I do have a manual, I have the original version of P6. The manual sucks thats why I asked this question. Because for a newbie/intermediate Photoshopper the manual is too difficult.

I know what an Alpha Channel is, after reading the manual, but I still don't understand what the great possibilities are. Do u get it?

Well I have yet to run into any GREAT possibilites, but as far as I can figure, it's just another selection tool, only it uses B&W.

Well, I shouldn't say that it's "just another selection tool" because I know that it is more than that, but to me it's just another selection tool with a few more possibilites.

Maybe a more advanced user could shed some more light on the subject.

Well if the aplha channel is anything like the one in flash. It is an opacity[sp] tool.. But that is just a guess

In flash you use the alpha effect to fade in or fade out a text

ok
open an existing RGB image

in the channel pallet click the little arrow pointing to the right at the topright of the pallet and select "new channel"

it will name the new channel "alpha1" (you can make the "mask" be represented by whatever color you want default is 50% red)

now you have an alpha channel (and like mattboy said its a cool way to do masks)

now in the channels pallet click on the "Alpha1" channel

double click the "eraser tool" and in the option pallet select "type = airbrush" (where it says "block" prolly)

select a large/soft brush in your brush pallet and make sure you have White as your background color

now paint(or erase) a couple of swipes down thru your image (on the Alpha1 channel)

and then on the channels pallet click where the eyeball should be to bring you original image back...it will be under the alpha channel.

you can make really tedious masks and duplicate them and have kind of a backup copy while you make changes to the mask.

you'll see the possibilities......

Alpha channels can also be used with the lighting effects filter to create 3d interfaces, text, buttons, etc.

For example, I created the 3d effect on this logo by using alpha channels and the lighting effects filter.

http://www.onceagainmusic.com/flashpageimage.jpg

Derek

very nice

The alpha channel can be as powerful as you make it.... I've found tons of uses for it...some cool.....some not..Lol!
just experiment with it ;)

Alpha Channels are simply a way to store selections. Even the R, G, & B or C, M, Y & K Channels are just potential selections, just waiting to be made active. Open a somewhat complex image, highlight any one of the channels and Command/CTRL-click on it or click on the "Dotted Circle" Icon at the bottom of the Channels Palette to see what I mean.

Also, try this:

In a new document, create any shape selection using whatever tools you want in your image window. Lasso, Marquees, whatever, and leave the "Marching Ants" active. Now, Open your Channels Palette and click on the second icon from the left, the "Dotted-Circle-on-a-shaded-square". You can now save this selection with the rest of your file, so you can work on it at a later time.

Believe me this comes in handy. I've worked on many images where I had to save a complex selection (such as selecting and masking around a fuzzy object) so that I could continue working on it the next day.

The following links may be of some use to you. Bookmark 'em!
http://www.zdjournals.com/ips/9811/ips98b1.htm
http://www.graphic-design.com/Photoshop/Tips/9807/106.html
http://macworld.zdnet.com/1998/02/create/4139.html
http://macworld.zdnet.com/1999/06/create/graphics1.html
http://ii.pmf.ukim.edu.mk/mcp/photoshop5/chapters/1-56205-723-5/ch01/ch01.htm
http://macworld.zdnet.com/1998/02/create/4139.html/