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Ali Maltz
Just another RL escapee
Join date: 25 Sep 2005
Posts: 23
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07-17-2006 14:43
From: Lo Jacobs Please check out this thread /109/8b/48537/1.html -- I never really had issues with alpha channels other than learning them, but this helped me to no end. Seconded. The linked thread talks about a replacement Targa plugin that modifies the way Photoshop saves Targa files. Long explanation: Photoshop deals with transparency really nicely within its own file format. For maximum flexibility, you can use vector or layer masks to non-destructively remove anything. When you save as Targa, though, you have to either manage your own alpha channels, or let Photoshop do it. By default, this latter option doesn't work well. Exporting to non-PSD formats, Photoshop takes the transparent image, flattens it onto a white background, then applies the alpha channel taken from the transparency. This is wrong is most cases. A 50% visible fully red pixel just got blended with white to become a 50% visible *pink* pixel, causing halos. Anyway, the linked thread offers an alternative Targa plugin that does the "solidifying" trick behind the scenes, at export time, using the built-in Photoshop transparency to create a *clean* alpha channel. Works a treat. The PC version is up-front, the Mac version a little further down the thread.
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Robin Sojourner
Registered User
Join date: 16 Sep 2004
Posts: 1,080
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07-17-2006 16:01
ARUUUUUGGGHHHH!
Don't, repeat, DON'T use that horrible, hideous, misbegotten, ill-conceived travesty of a targa plug-in!
It will make your files incompatible with nearly everything, because it embeds the Alpha, instead of making a simple, easy to work with, visible, modifiable Alpha Channel. Adobe realized it's mistake within days of releasing that thing, when people all over the place began to report broken .tgas that didn't work with most software programs.
They fixed it, weeks after the release, and have never repeated their mistake.
But, for some reason, people in this forum (and, as far as I know only in this forum,) insist on using it because, for some reason, it appears to work (at least for now) with Second Life.
I think that the people who use it imagine that it saves them time, or something. But it doesn't. I've written an action, specifically for people who can't be bothered to learn how to make an Alpha Channel, that will make a .tga file that's compatible with everything in a single mouse click.
So please, please, please, allow the thread that links to the thing to die. Or, if you must go there, read the entire thread, where Chosen shows you what that plug-in will do to your files, and why there is no fixing them after you've used it.
And don't waste your hard work by using a plug-in that will ultimately ruin your files.
Please.
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Ivy Contepomi
Registered User
Join date: 12 Aug 2007
Posts: 19
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I know this thread is wayyy old
03-09-2008 14:59
Don't throw things at me if I'm not doing this right; or if its wrong to "bump" an old thread. I'm having problems with the alpha channels and halos, and every step I follow in the tutorial....isn't working. I'm pretty sure this is me just not "getting" it. I'll use a really basic example of whats happening to me. This is the shirt I'm using (ignore the obvious problems  ). I am, naturally, getting halos when this is upload. I create the alpha channel; no problem whatsoever there. Show on the channel palette, all the right stuff checked, and I'm not using the horrible version 7.0. But when I solidify, I get a mess, and it doesn't work at all when uploaded, except to clothe the avatar entirely in gray and smudgy blue. Image one is here: http://img.photobucket.com/albums/v484/sskatygirl/imagenumber1.jpgThats how it is before solidifying. After solidifying, here's the horrible mess: http://img.photobucket.com/albums/v484/sskatygirl/imagenumber2.jpgAny help... is greatly appreciated.
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Void Singer
Int vSelf = Sing(void);
Join date: 24 Sep 2005
Posts: 6,973
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03-09-2008 16:50
instead of solidify, just manually extend your colors beyond the template borders, as that's where the halo occurs. those edges you see on the template are not perfect and subject to flex depending on shape
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Chosen Few
Alpha Channel Slave
Join date: 16 Jan 2004
Posts: 7,496
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03-09-2008 17:18
I'vy, your Image Two looks perfect to me. What you're seeing is exactly what I'd expect from Solidify. It may look like "a mess", as you put it, to the naked eye, but that's only because Photoshop doesn't know that your alpha channel is a transparency map (which is also perfectly normal). So it's showing you all the color information as totally opaque.
Don't confuse in your own mind the difference between the color maps (the RGB channels) and the transparency map (the alpha channel). In SL, the color maps will have nothing to do with transparency at all. The ONLY transparency you'll see will be governed by what's happening on the alpha channel. It's important to drill that concept into your head.
With that in mind, take a look at your Image Two. Notice on your Channels palette, the alpha channel is perfectly intact. Solidify didn't change it. Only the color channels have been affected. What Solidify does is it extrudes the colors from the edges of the opaque parts through the transparent parts, in the color channels only. This makes the colors "solid" across the canvas, which will prevent haloing. The alpha channel is now allowed to do its job, properly, without you having to worry about halos creeping in from the "transparent" parts of the color channels.
The important thing to remember is that when you bring the image into SL, the alpha channel will be the only transparency map. Where the white pixels are on the alpha, you'll have opacity, and where the black pixels are, you'll see transparency. So the "borders" of your shirt will be just where you want them. The "mess" will appear totally clean, and there won't be any haloing.
If you'd like to see the alpha channel as transparency directly in PS, copy it to a mask. In your Image Two, do the following:
1. In the Channels palette, ctrl-click on the thumbnail for Alpha 1 to select the whole channel.
2. In the Layers palette, if your image currently has more than one layer, put all your layers into a group. If it only has one layer, then don't bother with the grouping; there's no need.
3. At the bottom of the Layers palette, click on the Add Layer Mask Button, the one that looks like a gray rectangle with a white circle in it. A new mask will form in the shape of your selection, which in this case, means the mask will be an exact copy of the alpha channel, since that's where your selection came from.
You should now see the transparency in the image in PS. Remember, though, masking in this way is not something you want to do permanently. Use it only for testing purposes in your working document. Do not have the mask applied when you output to TGA, or your solidification will be undone, and you'll end up with a white halo. Remember to turn the mask off, or delete it entirely, before saving to TGA.
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Robin Sojourner
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Join date: 16 Sep 2004
Posts: 1,080
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03-09-2008 17:48
Ivy, as Chosen said, your image is perfect. Solidify did exactly what it should, and your alpha channel is intact, and shows exactly what it should.
If you're not seeing it perfectly when you upload, then I have to ask, are you sure you're uploading as a 32 bit TGA file? Anything else, and you won't get the Alpha channel you've so carefully prepared.
It needs to be 32 bits, because it takes 8 bits per channel. With the Alpha, you've got four channels (Red, Green, Blue and Alpha) and 8x4=32. So, if you're accidentally using a 24 bit image on the upload, you're eliminating your Alpha channel at that step.
The same is true if you don't make sure that "Save Alpha" is checked when you save the 32 bit Targa. It must be checked, or the Alpha won't be saved, even if you use 32 bits.
If you're using PNG, that format uses the image transparency to drive the transparency in SL (more or less) so you'd lose the Alpha channel there, too.
If you're using JPG, I don't think that supports the Alpha either. I'm not sure, because I've never used it to upload to SL. It's a lossy format, and since everything we upload is translated to JPG2000 anyway, you can see image degradation if you upload a .jpg. I highly recommend that you don't use it at all.
Other than that, I can't think of what might be going wrong. Your image is perfectly prepared, you're not using PS 7.0, so if it's not a question of saving in the wrong format, I'm stumped.
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JL Roffo
Registered User
Join date: 25 Apr 2007
Posts: 3
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03-11-2008 00:37
From: Robin Sojourner
If you're using PNG, that format uses the image transparency to drive the transparency in SL (more or less) so you'd lose the Alpha channel there, too.
Yes, but you get an EXCELLENT transparency. Im actually doing all my transparencies in CS3 using a transparent background, make as many layers i need to make things work the way i want (keeping the transparencies) and save the whole thing as PNG. Works like a charm. I actually tested personally (wasnt needed but i wanted to see if it worked  ) up to 6 layers plus the background and wham ! Perfect. Even with text layer rasterized and effected with Eye Candy or whatever. So where am I wrong ?
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Chosen Few
Alpha Channel Slave
Join date: 16 Jan 2004
Posts: 7,496
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03-11-2008 05:55
From: JL Roffo Yes, but you get an EXCELLENT transparency. Im actually doing all my transparencies in CS3 using a transparent background, make as many layers i need to make things work the way i want (keeping the transparencies) and save the whole thing as PNG. Works like a charm. I actually tested personally (wasnt needed but i wanted to see if it worked  ) up to 6 layers plus the background and wham ! Perfect. Even with text layer rasterized and effected with Eye Candy or whatever. So where am I wrong ? You're not "wrong". It's just important to realize that when you use simple transparency, you're sacrificing a lot of power and control. Also you often sacrifice speed. Working with a purely WYSIWYG methodology can be clumsy and time-consuming compared to working with an alpha map methodology. For a simple example, let's say you've got an image in which you want the transparency to grade smoothly from fully opaque at one end to fully transparent at the other. If you're using WYSIWYG, that could take a really long time to create, and it's unlikely you'd be able to make the gradation be perfectly smooth and uniform. But with an alpha channel, the entire operation would take less than a second, and the results would be perfect. All you'd need to do would be to apply a black-to-white gradient to the channel, and you're done. Of course, some people would argue back, "Well, if I need an effect like that, I'll just use a layer mask." That would certainly work, too. The reason that argument is a little silly, though, in my opinion, is that the logic behind making a mask is exactly the same as that of making an alpha channel. Either way, you're using a grayscale map as a proxy for transparency levels. If you're gonna do that anyway, why not complete the logic, and use alpha channels? Also, if you're going to mask an entire image, not just a single layer, then using a layer mask to do it instead of using a channel can take longer, and can be more destructive. In order to apply a layer mask to all the layers in the image, you either need to flatten the whole thing, or at the very least group your layers all together. Using a channel will save you those steps. I guess the biggest difference, at least mentally, between the WYSIWYG approach and the alpha approach is the concept of working additively or subtractively. With the procedure you described, JL, you must think of the image as being transparent from the start, and then you're adding in the opacity. With the alpha channel mentaility, the thought is that image as entirely opaque from the start, and then the alpha channel has the job of subtracting out the transparency. Oh, and by the way, I'm not sure if you meant it this way or not, but your post seemed to imply that you feel having six layers in an image is a lot. Just so you know, that amount is very, very, very small. It's not uncommon for a texture source image to contain several dozen, or even several hundred, layers.
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Robin Sojourner
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Join date: 16 Sep 2004
Posts: 1,080
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03-11-2008 10:32
JL, as Chosen said, nothing "wrong". It's just another way to work. But if you do go that route, then the Flaming Pear filter won't help you. (Read the OP's question, and you'll see that was the problem. I was just pointing out one reason why things might be turning out the way they were.) I always use the Alpha channel, not .png, for a number of reasons. For one thing, I like using the Flaming Pear filter, because if I've extracted an image from a photo I've taken (as opposed to just painting it from scratch) and I still have some background color on the edge pixels, Solidify will make that obvious. That's when I know I have to run "Defringe..." (Layers > Matting > Defringe...) to get rid of it. I can't always see that, because my eyes aren't as sharp as I'd like them to be.  Alpha channels also save me considerable time. Without them, I'd constantly have to turn Locked Transparency on and off, or erase around the edges of things, so that the ends of long strokes wouldn't make the image look messy and unprofessional. As it is, I can use a solid color layer to mask all of that on the edges of garments, and the Alpha will make the transparency for me. (Leaving a nice shadow, to differentiate the garment from the garment or skin beneath it.) It also keeps file size down. My clothing files typically have 40 to 60 layers, and if I had to put masks on even half of them it would really add up. It's far more efficient to have a single alpha layer. So yeah, if you're doing an image that has half a dozen layers or less, you might find it faster and easier to use .png. But when you start really getting into the power and flexibility of PS, using dozens and dozens of layers, you'll find that knowing how to make an Alpha Channel is well worth it.  Hope this helps!
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Robin (Sojourner) Wood www.robinwood.com"Second Life ... is an Internet-based virtual world ... and a libertarian anarchy..." Wikipedia
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Ivy Contepomi
Registered User
Join date: 12 Aug 2007
Posts: 19
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03-15-2008 05:59
I swear I had it on 32, but perhaps that was the problem. When I started again, going through everything from scratch, it worked perfectly, and looked fine when uploaded.
Thanks for all your help!!
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