Why would this not work in Photoshop?

I just read the thread about a question for Photoshop by Katanazia McKenna. I didn't want to get thread drift going and since I don't use Photoshop I really have no answers or tips that would help. Okay..........my question: Why can you not place an alpha channel before you begin making or modifying any texture? Open as layer (a transparent layer) first after you open your UV template of choice and place all your other layers on top of that layer?

I use the GIMP 2.2 and I'm such a novice at this texturing stuff it's really almost sickening. I read everywhere in these forums about photoshop's halo........and ways to eliminate it. It might be that it's just something that happens with PS but I've never had that effect in anything I do in GIMP. When I cut something from my layer I cut to the transparent layer under it...........sharp, crisp edges every time.

I want to ask if that can be done in Photoshop too..............placing an alpha (clear) channel down under everything (but over your template). I'm also sort of afraid to ask too.........if it were that easy surely someone would have figured it out already. So my assumption is that it won't work with PS............but that brings up a second question: Why not?

Thanks............I'm curious more than anything but someday I would love to get Photoshop and that might get me a slight jump on my learning curve.

By your questions, you seem to be a little confused about the concept of how channels differ from layers, and how layer transparency differs from overall image transparency. Let me see if I can clear things up a little for you.


You can. Channels can be made at any time. They're just grayscale data maps. You can do whatever you want with them at any time during the image creation process. It's just typically more sensible to make your transparency channel as a last step since it's usually a bit difficult to know where your transparent areas and opaque areas need to be before you've put everything else in.

Judging by your next question though, the question I just answered wasn't really what you were trying to ask.



The presence of one more transparent layer won't affect how the image turns out in any way. All it will do is increase the PSD file size a little. That's it.

As I was getting at in the beginning, layer transparency has nothing to do with TGA image transparency. TGA files are inherently layerless, so there's no way that any layer property, whether it be transparency or anything else, can have any affect on them.

Also, there's no way to place a channel "under" anything. Channels do not stack the way layers do. Again, they are nothing more than data maps, and as such they ALWAYS affect the image as a whole.


I would encourage you not to snicker. The fact that the halo exists is because Photoshop is doing its job. It's anti-aliasing pixels, just like it's supposed to, perfectly normal behavior. If it weren't doing that, something would be very wrong. Taking the extra split second to eliminate the halo (or more accurately make it look the way you want it to look since it's always going to be there) is not only painless, but it's a very important thing to be able to do. If GIMP doesn't let you do it, consider it a weakness of GIMP.

I know that may sound really strange, and probably all kinds of wrong to you, given that you're probably only looking at this from the viewpoint of Second Life texturing, but trust me, that anti-aliasing behavior is extremely important to have under user control.

One reason my transparency guide still doesn't have a GIMP tutorial, by the way, is that I have yet to figure out how to achieve that level of control in GIMP. It seems to always want to try to automate the process by copying layer transparency data straight to the alpha channel, and while on the surface that may seem like it makes things easier, it severely handicaps you in many ways. I'd be really surprised if GIMP were incapable of doing it "the right way", but so far I haven't figured out how to get it to do it.



Don't be afraid to ask. Your assumption is correct in that your described technique won't work, and the reason it won't work is important.

First, as I said before, TGA files have no understanding of what layers are. If you're a TGA, all you know is two dimensions, not three. You can't possibly fathom how transparency could come from a layer since in your world there's no such thing as a layer. All you know about as a TGA is channels. You've got three for color, and if you're one of those extra cool TGA's who gets to sit in the back of the bus with all your cool TGA buddies, you get to have a fourth channel for transparency, woohoo (but don't sit too close together, or you'll have sorting problems). When you're a TGA, there's no such thing as layers in your universe. You've never heard of them, and you don't care if you ever do.

Second, again, you can't put a channel "under" anything. Channels describe the actual pixels that constitute an image. They do not have height in any stack, certainly not in the layer stack.

For a metaphor that might help explain the difference between layers and channels, did you ever see the movie "The Craft"? Remember what one of the girls said about the spirt, Manon? "If God and the Devil were playing football, Manon would be the stadium and the sun shining down on them." Well, if all the layers in an image were playing football, the channels would be the stadium and the sun shining down on them. Layers describe the items in an image; channels describe the properties of the image itself.



I hope all this has helped you understand a little better.

I have never used the GIMP, so I don't know how things are done there.

But in PS, unless you have a Background layer, everything is built on Transparent layers. You can fill them completely, and make them non-transparent, but if you use the eraser on them, it erases to transparency unless you have Layer Transparency locked (in which case it erases to the Background color.)

This is true whether or not you have any Alpha channels. (You can have as many of them as you want; you just can't make a .tga file with more than one.)

So I don't really understand what your question is.

You can make an Alpha first, if you so desire. But ti won't affect the haloing at all.

That happens because the Targa (.tga) file format doesn't support layers.

When a file is made into a .tga file, it has to be flattened first. I have no idea how the GIMP flattens files, but PS flattens them onto white. The amount of white visible depends on the transparency of each pixel, with 100% transparent becoming completely white.

Think of the image as a stack of acetate sheets, with various opaque and semi-transparent inks on them. Flattening the image is exactly like putting them all down on a white piece of paper. So, if you have something that is red, but 50% transparent, it becomes pink.

The anti-aliased edges of most images are semi-transparent; which is where the white halo comes from. They are still semi-transparent in SL, but instead of being red that's 50% transparent, you now have 50% transparent pink.

The fix is so simple that it's trivial; make an opaque layer at the bottom of the stack with all the colors of the layers above it, so you don't see the white "paper" at all when the image is flattened.

You can even automate the process, so that all you need to do is click a single "play" button, or hit a hot-key, and the image will copy itself, make its own alpha, merge the layers, run the Flaming Pear filter to make them opaque, and flatten itself, so it's all ready to upload. It doesn't get easier than that.

The people who are struggling with this simply don't understand how effortless it is. It's not a weakness in PS; it's a gap in their knowledge, which can be quickly filled.

Hope this helps!

Hahaha....................Y'all helped all right Showed me how little I know. But actually I do know the difference between layers and channels. For the most part I think I followed what you said. I'm no graphics artist..........until just a couple months ago my total experience with imaging programs was Windows Picture and Fax viewer. And that's really not an exaggeration!! I have "learned" to do what I do by experiment and trial and error. I, one day, hope to get Photoshop (mostly because it's got the reputation of being the standard of standards for graphics) and was curious about that dreaded halo everyone seems to fight with...........I haven't experienced it with GIMP and was wondering why. It seems from Chosen that the reason is that GIMP just doesn't do stuff the way PS does. That more or less answered my question.

I wasn't being smirky about not having the trouble with GIMP that some have with PS. It's just true that I haven't had those problems. I just told what I do with what I have and that it works for me.......and when I get PS some day it probably will not work for me anymore.

Thanks for the information........I love reading you guys.

Peggy

I feel very presumptuous trying to add to what Chosen and Robin have already said but it occurs to me that the reason you don't get a halo in Gimp could be that you are not using antialiasing at all. You could do the same in Photoshop (I assume) or Paint Shop Pro (which I use) but then you would lose the smoothing that antialiasing gives you.

Just a thought

Suzi