Need help with alpha channel

I'm trying to make a simple texture. Just a text sign on a transparent background. When I use the texture in SL all I want to show is the text. Can someone tell me how to do this in either Photoshop CS2 or PSP7 ?

I tried several times and saved in tga format, but it keeps losing the alpha channel.

Any help would be greatly appreciated.

Make sure you actually have an alpha channel, on the channels pallette, and save in 32-bit TGA format. For full details, there is a sticky topic on transparency at the head of this forum.

I do have a alpha channel on the channels pallette, but it still does not work after I save.

How are you defining "losing the alpha channel"? What exactly is happening?

The important things are: SAVE the selection and export 32 bit TGA.
For example open a new file, type in your text on a separate layer from background layer, or past in the imagesign...whatever,
load the selction of that type/object and save the selection.

Export 32 tga

That's it!

ditch cs2 and psp for alpha chanels... gimp all the way..
3 button presses and its done... contact me in world for a free book on how to do it with all the nice colour pictures.
basically its GET GIMP FOR FREE (google it)
load your piccie.

then 5th icon along top row click it.
click the background.
goto LAYER/TRANSPARENCY and select it.
then select the rubber option
bottom row 4th along.
rub out all background.
then goto SAVE AS
just change the extension from whatever to .TGA

thats it.

i have literally hundreds of alpha siggns and logos and things at my shop done like this.absolutely has no ghosting ect... and its free as well.

just copy the pic into an alpha channel.........

when i begin a new project, in targa fashion, i immediately duplicate the background layer & delete the original. work with your unlocked layer.
remember when saving you mark the 32 bit and not check the compress button before you hit ok.
hope that helps, if that was the issue

You all make it sound so easy, and I agree it should be, but for some reason I can't get it to work right. Here is exactly what I did using Photoshop CS2:

Here is the image I used: http://www.papatron.com/test.jpg

1. File, open...and I select my image.
2. Change background image to layer by double clicking it in layers palette.
3. Use magic wand and invert.
4. Click on 'add vector mask' (circle in a square icon) at bottom of layers palette.
5. Save as tga 32 bit image.

At this point I can see the red text on a transparent background. However, when I attempt to upload to SL the text appears to be on a solid white background.

Thanks again for all your help. And Happy Thanksgiving everyone.

Try it this way:

1. File, open...and I select my image.
2. Select Menu --> Color Range and click on the white area
3. On the channels pallette, Click on 'add vector mask' (circle in a square icon) at bottom of the palette.
4. Select all on the mask you just created, and invert
5. Save as tga 32 bit image.

That should work. At least, it does in Photoshop 7

Normally I would do the text against a transparent background, not white, and have a layer below that which is solid-filled with black (to eliminate the halo effect). Then I can do it in 4 steps:

1. File, open...and I select my image.
2. In the Layers pallette, right click the picture icon for the layer, and choose "Select Layer Transparency".
3. On the channels pallette, Click on 'add vector mask' (circle in a square icon) at bottom of the palette.
4. Save as tga 32 bit image.

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Tron, your problem is that at no time in your steps did you actually create an alpha channel. You were working on the Layers Palette, not the Channels Palette, so you made a layer mask, not an alpha channel.

Masks and alpha channels perform similar functions, but they are two entirely different things. Mask affect only an assigned layer (or group of layers); channels affect the image as a whole. Now, since TGA files are inherently flat, they have no layers. Therefore, there's no way a layer mask or any other layer-specific tool can possibly carry any weight within them.

To solve the problem, you need to create a real alpha channel instead of just a layer mask. Here's how your list of steps should read:

1. File, open...and I select my image.
   
   
   
2. Change background image to layer by double clicking it in layers palette.
   
   
   
3. Use magic wand and invert.
   
   
   
4. Go to the Channels Palette, NOT the Layers Palette, and click on "save selection as channel". It's the second button from the left at the bottom of the palette, the one that looks like a square with a circle in the middle.




5. Save as tga 32 bit image.

Now that that's out of the way, there are two additional tips I should mention. First, I recommend never using the magic wand. It's a very clumsy, imprecise tool. There are many other selection methods that work much better. For something as simple as the image in your link, it's probably okay to use, but for anything more complex, you'll quickly discover that it doesn't work very well at all.

Selection is a whole other topic though, so I won't get into it for now. Perhaps we should have a dedicated thread on that subject one day.

Second, by having a white background, you're very likely to end up with a white halo around the image. For the reasons why, and how to eliminate it, see the Transparency Guide, stickied at the top of this forum.

And speaking of the guide, it contains many different Photoshop tutorials for alpha channels. Follow any one of them exactly step by step, and you'll have very good results. When to use the Layers Palette vs. the Channels Palette is covered in detail in each one.

BINGO!!

Chosen Few, it worked. Thank you, thank you, thank you! It was so simple and I was missing it.

Thanks to all who took the time to help me.

Happy Holidays!

Glad you got it worked out, Tron.

Why "rub out" the background when all you have to do is open the Layer dialog box...right click the background layer, go to Transparency, and choose Color to Alpha, and then hit OK on the box that opens?

This brings up another question. How do I make this texture in CS2 from scratch? The image I'm using I made in PaintShop Pro 7 and opened it in CS2.

When I try to make this in CS2 it doesn't allow me to save in tga format for some reason. I think I'm just spinning my wheels. lol

If TGA is not a save option, the most likely cause is you're not working in RGB mode. Go Image -> Mode -> RGB Color. Also make sure 8 Bits/Channel is selected, not 16 or 32.

As for technique on the image itself, I'd recommend using a black background, and putting the text on its own layer. You won't have to bother with the magic wand or any of that; just create the text, and then ctrl-click the layer thumbnail (on the Layers Palette) to select everything on the layer. From there, click the button on the Channels Palette to create the new channel from the selection.

Thanks again Chosen. This worked just as you said. You really know your channels. lol

Since I have both. I can explain. Whe you try to save a tga in CS2 and the layers are merged, PS gripes and teh buttons are greyed out.
If you plan on working on the texture anymore , save as psd first. Then Merge ALL layers, then save. The alpha channel is still there. And it will save.
As for PSP 7, I am not sure. A little google digging and poof:
http://www.campratty.com/1faq/faqpages/a12.html

I still say, if you spent money of CS2, you should on PSP 11. You will like it. And if you are a 'argh, shiver me timbers,' you have no excuse either.
Its time to upgrade.