Photoshop alpha channel discovery

Hi folks. I just realised that creating an alpha channel in Photoshop is way easier than the tutorials mention.

Basically, the Background layer needs to be empty, or transparent. No need to go into the Channels tab to create the right shape for the alpha channel.

So here's what I do:

1. Create a new document

2. Unlock background layer, select all, delete (or just hide the background layer)

3. Create all other layers normally.

4. Save As Copy, TGA format, 32-bit

5. Upload into SL

That's it! Looks like Photoshop automatically creates the right alpha channel shape out of the transparent areas in the PSD. No need to manually create them in the channels tab. Yay!

I discovered this purely by accident since I once forgot to create the alpha channel before uploading. And it worked fine!

This is true - there's no need to get into setting up alpha channels in Photoshop, just set the background to transparent.

Here's an even easier approach when starting a new image:

1. New...

2 On the sizing screen which pops up, there's a contents heading. Pick transparent.

3. It's all set with a transparent background!

(This applies to version 7.0)

Actually, I believe this depends on the version of PS that you're using.

I tried this method with PS 5.5, and got an all-black alpha channel. (In other words, a 100% transparent texture)

This was not what I had intended.

Yes, sorry. I am using Photoshop v7.01

Oh, sorry. That sounds kind of accusatory, doesn't it?

I tried this weeks ago. It's not your fault that I tried it.

I just wanted to make sure others reading this thread would be informed that this is version-dependent.

Hehe! You didn't sound accusatory Grim. I just didn't realize it was version dependent...thanks for pointing that out!

Photoshop is a bit too pricy for me. Is Painshop Pro accepatable useable? Doesn anyone have any experience with Paintshop v7 vs v8?

Yes Satori.

Check out this tutorial here.

Eyes on Second Life

I made out a notecard with a photoshop alpha tutorial in it complete with screenshots. I used to hand it out at the texture classes I taught. I don't have time to do the classes anymore but if anyone would like the tutorial just IM in game and I'll send one your way

ooooooh. *save* Thanks, Steller!

ok, call me a dumb.. but what if i don't have save as 32 bit... i only have 24 bit... and when i reopen the file it has white where the clear part waas (

What software? PS or PSP??

24-bit is 16 million colors (8-bit red, 8-bit green, 8-bit blue)

32-bit is 16 million colors (8,8, + an 8-bit alpha channel.

In PSP, you have to do things a little differently. In PS, it may depend on which version you are using.

If you don't have the option to save as 32 bit, it sounds like you're probably using PSP. In that case, you'll have to manually create the alpha channel. You then save as 24-bit, but it will keep one alpha channel (if there is one.)

If there isn't an alpha channel defined, it will just automatically use whatever background color you have set for all transparent areas.

(Note, this is all for TGA. If you're saving BMP, you don't get alphas.)

ahha, well that was fast ;D thanks.. it's psp 8 so i guess i have to figure out how to set the color for the alpha
*need psp class

so much to learn.....

OK, in PSP, assuming you have an existing single-layer image with partial transparency the way you want it. (I'm using PSP 7. But this shouldn't be drastically different.)

1) In the menu, select Masks|New|From Image
2) In the "Add Mask From Image" dialog, select "This Window" and Source Opacity. Make sure "Invert Mask Data" is NOT checked.
3) In the menu, select Masks|Save to Alpha Channel, save the alpha channel using any name you want, it won't matter what the name is. Remember, you can only have one alpha channel.
4) In the menu, select Masks|Delete. When it asks you if you want to merge the mask into the current layer, select NO.

5) Save your image as a 24-bit Targa file. You'll get a warning telling you that the image will be combined down to a single layer, and only one alpha channel will be retained.

You can also get the same end result using selections instead of masks. Just select all, float, defloat, and you'll have a transparency-based selection that you can save to an alpha channel. This replaces steps 1 & 2 above, and you don't have to worry about accidentally merging a mask into your image.

Heya there, i can't seem to find a working tutorial for PS 6.0 on this subject.. I tried the first thing mentioned and same problem as grim completely transparent picture. Anyone able to help me out here?

Try this...

1. Follow the steps as outlined in the first post.

When your image is finished and ready to create the alpha and save do the following...

2. Make sure the bottom layer's visibility is turned off (click on the eye icon for that layer in the layer palette).

3. Select any of the top layers and in the layer palette menu do a "merge visible." You should now have only two layers with the bottom layer still turned off.

4. With the top layer selected go to the selection menu and do "load selection." In the dropdown list choose "layer 2 transparency"

5. In the selection menu do "save selection." The first saved selection automatically becomes the alpha channel.

6. Look in the Channels palette and make sure you now have an alpha channel in addition to the RGB channels.

7. Save as 32 bit TGA

Hope that helps

Consequently the behavior Driftwood is explaining is a bug with photoshop. They rectified it with a patch after shipping.

This was the original spec for the TGA file format and after many years of the wrong implimentation Adobe decided to fix it with 7.0, however this caused problems for all the game development studios and the patch was released. I recommend getting the patch from adobe and using the alpha channel as this is the proper functionality and what you are working with now will not be supported in future versions of Photoshop nor will these tga files be functional in many of your other paint applications.

Just don't save your master with the layers merged if you want to keep editing that file later!

I use the Image -> Duplicate... menu item and turn the "Duplicate Merged Layers Only" checkbox on.

That way, all you have to do is hide the layers you don't want to inlude in the final version (including any opaque background layers), pick this menu item and then add the alpha channel to the new document... And your original layered version is still intact.

Also, another way to make your alpha channel (no better, just different) is to control-click (command-click on Macs) the merged layer's icon in the layer palette, switch to the Channels tab in the same palette, open its pop-up menu and pick New Channel..., hit return, then hit delete. You should now have a white hole punched out of your back (or red) alpha channel. (If your current background color was the alpha color, you'll have to change it before hitting delete.)

The command-click on the layer's icon selects the layer's contents, preserving alpha information. Then with that selection still active, you are punching the opaque areas out of the alpha chanel you create by hitting delete there.

Oh, and one other tip: If you are making a simple text texture, and want to use the layer blending effects, make sure to merge that layer with an empty layer before making your alpha channel. Otherwise, the alpha will not include those effects, like drop shadows, and they won't show up in the final texture.

Oh, and before you save the TGA with the alpha channel, give it an opaque background with the edge colors of your image. For example, if you have black text on an otherwise transparent background, make an alpha chanel for them, and save it as a TGA... Your text will end up with a white fuzz around the edges. Giving the file a black background layer will make the whole image look black to you in photoshop (unless you hide the background layer), but the alpha channel will work better, and the fuzz will be black.

If you have green text, use a green background. Etc. For other shapes like a avatar cut out of a screenshot, you'll have to play with a background color that give you the best edge. Black is usually better than the default white.

As Neil mentioned, this behavior is a bug in Photoshop and has subsequently been fixed.

I've got some informaiton on Alpha Channels in my tutorial which I will be pulling out and expanding on to create a new tutorial just for alpha channels, since I believe they cannot be explained too much

I will also probably download PSP so I can add a PSP section to it as well.

Until then you can check out my tutorial (link in my sig below)

Yay!! I am looking forward to that!!