Transparency and Alpha Channels: The Definitive Guide

Chosen, did you ever get around to making a GIMP tutorial? I never did find the GIMPshop plug-in on the GIMP web page.

If you want to use it, avoid alphas altogether, I had to redo a texture just now because it had contained an alpha I couldn't even find, and I'd like to think I'm fairly well acquainted with GIMP (I know about the "remove alpha channel" tool).

Robby, please don't jump into a stickied thread about alpha channels, just to try to tell people not to use them. If you want to discuss alternative methodologies, please do so in a different thread. I'll be there, of course, to help smack some sense into people about exactly what you miss out on when you use simple transparency instead of taking the whole 2 seconds required to make a real transparency map, but I don't want to get into that kind of argument here. That's not what this thread is for.

All I will say on the subject here is that there about a million benefits that come from learning how to use alpha channels properly. There's only one (very insignificant) benefit from not learning them, just a small one-time savings in the mental energy it takes to learn ANYTHING for the first time. I think when you weigh that one-time savings against a lifetime of countless gains, it's pretty obvious that there's just no way the ignorance can be even remotely worthwhile. The knowledge is so much more valuable, the degree of benefit is beyond description.



Tundra, I'm afraid it will probably be quite a while before I'm able to add a tutorial for GIMP. I'm just not comfortable enough with that program to teach it. When I first wrote this guide, I had been planning to spend some serious time with GIMP to try to increase my comfort level, but now here we are a couple years later, and I still haven't done it. Sorry about that. I'd still like to do it, but I can't guarantee when it will be.

I meant I don't know any ways of saving a texture as a 32 bit .TGA in GIMP, only 24 bit, so I'd advise against using alphas if you use GIMP too, unless you know how to save them in 32 bit, in which case I'll take it all back if you tell me how to.

EDIT: I take it all back. "Once you have your image open, just right click on the layer in the layers dialog and select "add alpha channel." Then you will have a 32 bit file. Then, just File --> save as --> Targa TGA format" from the GIMP forum.

Does anyone know how to create transparent textures with Photoshop Elements 6? I've used the tutorial instructions for PSE 3 dozens of times with excellent results. With PSE 6, however, the third step of the tutorial ("On the Layers Palette, ctrl-click the thumbnail for the layer with the bikini on it." will not work. Control-clicking a thumbnail in PSE 6 results in a pop-up that gives some layer options, such as "Rename Layer" and "Duplicate Layer." This is different from PSE 3, in which a Control-click provides a pop-up with the "Select Layer Transparency" option.

By the way, I'm using a Mac. I don't think there should be a difference between Macs and PCs regarding these steps; there wasn't with PSE 3.

Wow! This is SO informative.
I'm using GIMP and am having a lot of luck with it.
I think it automatically gives me my alpha channels?
I'm still learning so please bear with me and correct me
if I'm wrong.
I'm sure I am!

But I'm learning so much.
It's overwhelming.

On a Mac, it should be cmd-click, not ctrl-click. Generally, for PC to Mac conversion, ctrl=cmd and alt=opt.

If they have indeed changed the functionality for PSE6, that would be unfortunate and annoying. When I get a chance, I'll download the trial and see what's new in version 6. I haven't looked at PSE since 5 came out.

In the mean time, could you please respond here, and say whether cmd-click works? Thanks.

I double-checked both versions. In PSE 3, it's Ctrl-click to "Select Layer Transparency" (a pop-up gives that and one other option, "Rename Layer." Cmd-click selects pixels on the layer.

In PSE 6 Cmd-click does the same thing as in PSE 3: selects the pixels. Ctrl-click gives a pop-up with more options than PSE 3 ("Rename," "Duplicate," and almost everything else in the Layer menu); "Select Layer Transparency" is not one of the options.

Searching on "transparency" and other relevant terms in the PSE 6 manual reveals instructions for creating PNG files, but nothing relating to the process I've used so often to create TGAs via the "Select Layer Transparency" command. I tried some PNG files, but I couldn't get rid of the white halos. They weren't as bad as TGA files that are created without any additional steps; but they aren't as good as using Flaming Pear's Solidify filter before saving as a TGA. I've just installed my old version of PSE 3 on my new Mac, and I'll leave it and PSE 6 on it for now.

Hi Chosen. Lately i have been noticing alot of textures that ppl are putting up to share as being .png files. Until the wave of new servers and new introductions of different grids i never had. How does this affect the way those of us who use photoshop and the other 2 main programs.

I'm not sure I understand your question, Em. Could you rephrase it?

It might be next Monday or so before I can reply, as I'll be at SLCC for the next few days, but if I can respond sooner, I will.

Can anybody help me? My alpha channel seems not working in CS4. I sued to use CS2.

What exactly is happening, Nieve?

So you know, CS4 and CS2 behave identically where alphas are concerned. The only one that was ever different was 7.0.

well as usual, if in CS2 i create alpha layer in Channel where I select the part to be transparent in black and the part i want it to be appear in white. then i select all the channel and save as TGA file (32 bit). This step always works when I was using CS2. When I upgrade it to CS4 (since my new laptop is on Vista), I try to use the same step but when I preview it in SL or SL Clothes Preview, It doesn't work at all because I can't see any part being transparent at all. Is there any extra step for CS4 that I miss out? IF anyone have tutprial on alpha channel for CS4 please let me know.

CS4 behaves exactly the same way as CS2 with respect to alpha channels. There are no CS4-specific alpha channel tutorials. That part of the program has not changed ever (except for in the short lived version 7.0, which was corrected three months after it was released). A Photoshop alpha channel tutorial written today would be identical to one written 5, 10, or 15 years ago. There's nothing new or different to add.

If your CS4 is behaving differently than it should, I can only think of three possible explanations:

1. User error. Maybe you're just doing something wrong.

2. Something is corrupted or incorrectly installed. Try uninstalling and reinstalling the program.

3. You borked your Photoshop by installing a bad plugin. What plugins have you installed?


If you're absolutely positive you're not doing anything incorrectly, you're completely sure your installation is good, and you haven't installed any plugins besides the ones that came with CS4, then I'm stumped for now.


If you'd care to start a new thread, I'll be happy to help you troubleshoot the problem. I'd rather not do it here, though. It just wouldn't be right to troubleshoot here in this stickied guide, since problem is definitely on your end, not something likely to affect everyone.

Once we've identified the cause of the problem, if it seems like something everyone should be made aware of, then by all means we should post the solution here. But there's no good reason to include all the intermediate back-and-forth chatter here. I hope that makes sense to you.

ok I understand about intermediate chatter. Just let me know which plugin that I need to look in order for my alpha channel to work. I try to send you a PM but you have off that feature.

The back and forth chatter is useful. It's just a little out of place for a stickied guide is all. Please start a new thread, so we can have the needed discussion there.


You're misunderstanding. I wasn't saying you need a plugin in order for it to work. If you did a standard installation of Photoshop, then everything you need should already be in place.

What I was asking is if you may have installed any ADDITIONAL plugins that could have screwed things up. For example, if you installed anything that promised to "make alpha channels easier" or to "automate alpha channels" or anything along those lines, that would have killed it. As has already been discussed at length in this thread and elsewhere on this forum, such things invariably destroy the normal and proper functionality of Photoshop. Do not ever try to use them.



Two things:

First, I'd rather have the discussion publicly than privately, so that it has a better chance of helping the most people possible. I just don't want to do it in this particular thread, since it wouldn't be appropriate.

Second, not that it really matters, but I never turned PM's off. My forum account is broken, and has been for several years now. I cannot send or receive PM's, and I can't view most attachments. The Lindens are absolutely clueless as to how to fix the problem.

As for additional plugin, I haven't isntall any beside brushes.

Hmmm Lindens seems to works in mysterious way.

By the way, my alpha channel problem is solved. Actually the problem is on my SL Clothes Viewer which I don't know why it display the whole texture in it. When I upload it in SL (just to gamble with the texture), my texture is absolutely fine. Anyway thanks for helping me out.

I'm glad you got your problem solved, but I'm a little disappointed that you wasted everyone's time by forcing the discussion about it to take place in this thread. I asked you several times to start a new thread, but you just kept on posting here. (And I had no choice but to respond, since I'm the one who maintians this thread. I can't just leave it hanging.) Please, please, please don't do that again. It's very important to keep these stickied guides on topic, lest they lose their meaning.

Also, kindly don't distort the facts of a problem when you're asking for help. You distinctly said in your first description of the issue that you couldn't see transparency "when previewing in SL or SLCP". But now we find out it was only SLCP that was malfunctioning, so theproblem had nothing to do with SL itself at all.

This discussion never should have taken place here (or really at all, since both Photoshop and SL were working perfectly the whole time). If you have any more to say on this subject, please start a new thread. It's not right to keep going with it here. Thank you.