Transparency and Alpha Channels: The Definitive Guide

Okay, here goes, since i use Ulead PhotoImpact (which i will call PI) as a paintprogram and there is no tutorial on that, i hope i might be able to explain how i make the alpha channels (using photoshopCS for that!!!) and to help others that use this program (or any other).

First of all i have opend all psd (or the ones you want to use) templates as "open the composite or first layer only", that way i only got a "background", resized them to 512 x 512 and saved them as a BMP file to a folder i created for them.
Okay now i have the templates as i want them to work on.

I open the desired template, click the Bezier Curve Tool, "draw" the clothing, click the toggle selection Mode icon, click Selection on top and hit Convert to Object (make also sure that preserve base image is marked).
Then i fill in the selection with a color, gradient texture or anything else i need.
Once i done all "drawing" i rightclick a selection (object) and hit Select all Objects, then rightclick again and hit Image Optimizer, click the PNG icon inthere (make sure that you hit transparant on older PI versions) and save it.

Okay the PI work is done and now i need to make an alpha channel, wherefor i use Photoshop CS.

Open the saved PNG file in Photoshop, also open the template you used for it in PI, drag the PNG file onto the template and place it on the right spot.
In the layers and channels palette,(if good thats allready opend in your photoshop) click on the layers tab, click the lil eye on the background layer (which is the template) it will hide the background and leave the PNG file.

Hit the Cntrl key on your keybpard together with the PNG layer in the layers palette, it will invert the selection.
Then click the channel tab, click the lill NEW icon down that tab, it will create the Alpha Channel (it shows all black).
Go to top >> Edit >>click fill, Use White, mode normal, opacity 100% (transparancy i always allready set on the drawing in PI).
Once done, save as a TGA file - 32 bits and its done.

Phew, i hope this isnt to confusing, its the way i do all my creations and it works perfect for me, and i hope i help some others this way.

PS: Why i save it as a PNG file and not as a GIF file, is because PNG saves the image as it is with all details and shadows etc.

Cloudy, while I appreciate the expansion of this subject into other programs besides just 'the big three', I gotta ask, why use two programs? If PhotoImpact can't do the whole job from start to finish, why use it at all? There's nothing in your description of your work-flow that couldn't be done entirely in Photoshop in almost the exact same way.

You can certainly draw vector paths in Photoshop, just like you're doing it in PI. That's what the pen tools are for. You can convert those paths to selections with one click, and the from there you can fill them, just like you were talking about. Depending on what look you're going for, you can even speed up the process by using shape layers, which will allow you to draw your paths and fill them all in a single step.

My memory is slightly fuzzy on how paths work in PSP and GIMP, since I haven't used them in a while (have yet to install them on my new machine), but I'm fairly sure the above is true in those programs as well.

So, what do you feel is the advantage of doing half the work in one program, and the other half in another? Since your method requires Photoshop anyway, wouldn't it be far simpler just to use that the whole way through?

I'm also curious what benefit you feel there is in flattening the templates. Being able to move the various components up and down in the layer stack, and being able to turn them on and off, while working is huge. In what way do you feel eliminating that ability is of help to you?

OK this is gonna sound like a total retard, yet WHAT clothing/skin template are you using?

i guess it surely aint the template fron Chip midnight?

Reason i flatten the templates is because ive never worked with layers really and the way i work i feel totally familiar with , so for me that works great Chosen. I appreciate your respond and totally understand what you are saying, for me thoo this way works perfect and i have no problem working in 2 programs.

Mira, you can use Chip's templates, Robin's, or the standard Linden Lab ones. You'll find the latter on the downloads section of this site. You can find Robin's at www.robinwood.com. It sounds like you already have Chip's.

Cloudy, thanks for your answer. Always interesting to see what different people are doing. Your way wouldn't be good for me, but if it's working for you, great.

Just wanted to let you know that at last I finally am able to make my clothes somewhat see through. My first attempt the guys would have liked, my top was completely invisible .

In doing it I am using 2 programs, PSE4 and GIMP. I use GIMP to fill my alpha channel to the degree I want it to be. I am sure that part can be done is PSE4, but for now I am just happy I can do it at all. Once again thanks for all the help that has been offered here.

Kat

I don't know if this is the place to ask this. I'm familiar with alpha channels from making things for The Sims 1 and 2. I usually don't bother with masks but just make my image in my ancient PSP7 by putting no color where I want it transparent and moving the sliders on the layers I want to be translucent. Then save it as a .psd file, open it in The Gimp and save it as a .tga. It works ok for me.
What I want to ask is about is prim skirts. I've seen some great ones with scalloped edges, lace cut outs and so on. My skirt skirt prims with transparency on the texture have a "bleed through" problem I'm also familiar with from my experience making Sims 2 objects. The surface on the outside of the hollow, cut cylindrical prim becomes invisible in the wrong place and the surface of the inside shows through. This happens even when I'm looking at only one prim. I'm wondering how other designers get around it.

Kaimi> What you describe is a very common issue and there's not much in the way of a solution except from just avoiding the use of textures with alpha areas. In-world you'll often see parts of people's hair doing the 'alpha fighting' thing and it's especially apparent if you happen to walk in front of a building that uses an alpha texture.

I've pretty much given up putting textures with alphas on prim skirts. If there is a solution I'd love to hear it though! I have some gorgeous gowns from fairly popular designers but they have alpha textures on them and if I stand in front of a building with windows or a tree I sometimes look like I'm wearing nothing but my underwear!

Thanks Merry, I was afraid of that. - but hoping for a magic cure lol.

To add a little to what Merry said, what you're talking about is an OpenGL glitch in what's known as alpha sorting. It affects nearly all OpenGL applications, including video games, and even expensive professional 3D modeling programs. So you know, there's a description of what causes it in the FAQ section of this thread.

I did want to address one additional thing from your post. You mentioned you're using PS7 to do most of your work, and then you're firing up GIMP for TGA output. So you're aware, there's no need to use both programs. Either one alone will do the job from start to finish; it's just that PS 7.0 is broken (this is in the FAQ as well). All you need to do is upgrade it to version 7.0.1 via the free patch from adobe.com, and then it will be able to save TGA's with alpha channels properly.

Oh yeah I saw that as I was reading through the thread. I think there was even a link to where to download it... Thanks, Chosen

Okay,

I got something by using the Chip Midnight Template and then making a mask layer and getting it saved to alpha. When I put in the black background I get a black shirt with the transparency I wanted. My actual question from previous posts was how do I, make the artwork, painting, whatever I'm using appear in the black background or over it? This is as far as I've gotten and still no mountains made from molehills. But little success aside from black tee shirts with designs and odd transparencies. I know how to make and use the mask, just don't know how to put anything over it.

Hi Zuriel. Once again, this is not going to be the answer you want to hear, but it would be irresponsible of me not to say it. Take a step back, and spend time learning how PSP (and raster editing in general) works before you proceed any further with trying to learn texturing for 3D. I can promise you that attempting to learn all this stuff out of order will be a tremendous handicap to you. It might not seem like it now, but the basics that you're skipping over here at the beginning will cause problems for you that will get exponentially worse as time goes on, and you move into more and more advanced territory.

You can learn the basics relatively quickly, by the way, so don't feel like doing it will slow you down. In fact, you'll find the opposite is true. By taking a few small steps back to the beginning now, you'll be able to take a giant leap later on. The firmer your grasp of the concepts of 2D raster editing, the faster you'll be able to learn 3D texturing. The first garment I made in SL (a fairly realistic red satin bra) took me less than an hour to make, even though I had never even so much as looked at the templates before. It was only because I already knew how Photoshop worked that I was able to do that. Had I not already had that knowledge, the same item would have taken weeks.

Anyway, to answer the question (which I really shouldn't since it's well below the scope of this thread, but I will since I'm nice), open up the Layers Palette. You'll see that the names of all your layers are arranged in order. This list is called the "layer stack". Within the stack, you can drag individual layers (or groups of layers) up and down to change their order. The layer that's listed at the top of the stack will be the same one that appears on top of all the other layers on the canvas. So, if your black layer is on top, but you want it on the bottom, simply drag it to the bottom of the stack in the Layers Palette, and it will also move underneath all the other layers on the canvas.

Think of it kind of like shuffling cards. The deck is the layer stack. If you've got a card at the top of the deck that you'd prefer be at the bottom, simply pick it up and move it there.

If any part of the third paragraph in this post is over your head, consider it proof that you're absolutely going to need to follow the advice in the first two paragraphs. Learn the basics of 2D raster editing before you attempt to learn to texture for 3D. The latter builds upon the former. Trying to learn both at once is a formula for disaster, as I said before.

I'll do that,

I will admit though I was able to make a few things that at least helped me understand how the mask worked after the fact. And just so I'm clear, 2D are pictures and such. You suggest I edit and learn the program one them. I'm taking the time to edit a whole folder of images I wanted to use paint for but have PSP now. Thanks for the help though, I did manage to figure out the mask save for where my transparency ended, I could see it in the layers palette but had just a bit of trouble on figuring my lines out. Thanks for being patient with a n00b, now off I go to learn this thing.

Glad to hear it, Zuriel. When you've got a good handle on PSP, and you're ready to take the next step and start texturing again, you're probably gonna have all kinds of questions you wouldn't have thought of now. By all means, I hope you'll come on back and post them.

I'm having some difficulty using this as a guide in gimp so if you're still thinking or working on that one it would be great!

otherwise I'm re-reading this a fewmore times to ry and figure it out.

i just wanna say thaaaaaaaaaaaaaank you very much pal

i really spent soooo much time trying to figure out this.....
you made it sooo much easy and did a perfect job

Hi - I have read and appreciate beyond description your tutorial on transparency!
I have followed your directions many times and also that of Robin Sojourner, so I am confident at this point I haven't made the mistake. But something is amiss! When I have completed the steps (trying to make a simple iron fence) I go to save as a TGA and I get a somewhat lengthy message window about due to limitations it must merge. (I am sorry I didnt write this down word for word) I have no idea what to do about this. I am new to Paint Shop Pro and using textures in SL. What do I do next to resolve this?
Thanks for any help - Lux

Chances are what you're seeing, Lux, is the warning prompt that the TGA will save as a flattened copy. It's nothing to worry about. TGA files are inherently layerless, so the system is just warning you that your outputted file won't preserve your layers. To keep your layers intact, always save an archival copy in PSD format or in PSP's native format in addition to TGA. The TGA is for SL; the PSD is for you.

Thank you for the response and valued info!
So this is not the reason my saves come out one color (usually the dark gray layer color) and/or still show white in SL and not transparent. ARGH!! Back to the drawing board so to speak. Please help if you can!!

Frustrated and Alpha crazed - Lux

If your images are not showing transparency in SL, then you've either got too many or too few channels. For the transparency to work, you need exactly four channels, no more no less.

Follow the tutorials step by step without changing a single thing. Don't forget to save your alpha channel, make sure you don't have more than one alpha channel present, and don't forget to save as 32-bit TGA. If you save as 24-bit, you'll be erasing the fourth channel (8 bits per channel, 8x4=32).

If you're still confused, post the exact steps that you're taking in your work flow, and either I'll be able to tell you where you're going wrong.

Hiya Chosen and thank you for all you've done here HuGs! I have a question though. I'm using PSP X and I go step by step in your tutorial and it is not working. When I upload the file(TGA) what I see is The image in the middle is transparent and outer edge is black? I've done it all step by step over and over. whats really strange is 1 out of 10 works? I just printed out the tutorial and tried it 5 times and still nothing can you help? I see the above person is having the same problem as I hummm.
What I do notice is that the Image says RGB 8 Bits/Channel Thats 24 right? also its 1 Layer and one alpha. < thats after I save it as TGA. This one happened to work. As for other Images they say the same thing only they dont show in SL properly. You dont mention anyting about loading the Alpha so I'm guessing it does this when you save it. This has been very fustriating and I'm on my ropes end. I've read al the posts and I do understand Layers, Mask and Alpha. The grey to black issues as well? Is it possible SL is having an issue?
One last thing, When saving I see where there is an option to save as 8,16,or 24 Bit But NOT 32. If I choose nothing its defualt is 24. If I bring it back up in PSP and view the Image Information it says TGA, RGB 8 Bit/channel, Layers 1, Alpha 1> this is 32?

I've edited this a few times so as to add as much information as I could to better give you an understanding as to my problem. Hope I did'nt confuse you by doing so because I might have to myself


Again Thanks for all your help you've been giving to us noobs. I'm more excited about SL then I have ever been.

That's strange. If I'm reading you right, you're saying the part that should be opaque is transparent, and the part that should be transparent is opaque, correct?

Are you by chance in Canada? I think the alpha channel standard for some Canadian-made software used to be the opposite of everyone else's. White meant transparent, and black meant opaque. That really shouldn't affect PSP though, and certainly not a version as recent as 10.

Try inverting your alpha channel, and see if it solves the problem. Perhaps you made it in reverse to start?


Unless I'm reading one of you wrong, Lux's problem is actually different from yours. Lux is not getting transparency at all, whereas you are getting it, but it's in the wrong place. At least, that's my interpretation of what you both are saying. If I'm misunderstanding you, tell me.


Technically, yes, RGB is 3 channels, which times 8 bits per channel equals 24 bits. However, some programs, PSP included I think, make no distinction between RGB and RGBA. They just end up calling both "RGB". Technically, a color image that contains an alpha channel should be referred to as RGBA (32-bit), not RGB (24-bit).


That's how it should be.


I'm not sure what you mean by "loading the alpha". When you create your mask, and then save it to an alpha channel, that should be all you need. Then when you save the file, PSP should retain all the channels, including the alpha channel. Unfortunately though, since PSP has no channels palette, it can be hard to tell just how many channels you have.

When you export to TGA, you'll either have three channels or four, since four is the maximum that the TGA file format supports, and three are required for a color image (the fourth is the alpha). If you had more than four channels to start with, then the alpha channel in your TGA won't be right. In most cases, you'll end up with the alpha being completely white, which means no transparency. By the sound of it, that's what Lux's problem was, too many channels to start with. It has to be four and only four if you want transparency.


I'm not sure what you mean by "gray to black issues". It's probably not relevant to your problem, but just in case, care to clarify?


Possible, but highly unlikely. It's more likely you made a mistake somewhere along the line in your work flow. I can guess at what the mistake might have been, but without knowing more about what you actually did, I can't say for certain. It sounds to me like your alpha channel is inverted (black where white should be, white where black should be), but I'm quite sure how it would have ended up that way.


Yeah, for some silly reason, the save dialog in some versions of PSP does not give you an option for 32 bits. In that case, choose 24, and as long as there's an alpha channel present, it will actually be 32.

PSP has made a lot of progress in recent years towards becoming what I would consider to be a professional grade graphics program, but it's still got some flaws. Its lack of a channels palette and its lack of any universal understanding of what alpha channels are (from its incorrect help documentation to its incomplete save dialog) are perfect examples of why it's not there yet.


I think I followed it, but if I misinterpreted anything, let me know.



You're welcome. Glad to be of help where I can.

Ok this is a question for a friend....I was talking them through how to create an alpha channel on msn voice last night, all went well until they got to the point of saving. If they selected .tga as their format it would only allow them to save as a copy and not select to save alpha channel. I am sure I have seen something about this being a preferences thing that needs to be set in CS2, but looking at my settings and his I could see no difference between the two.

Does anyone have any suggestions ? My poor friend is so close to getting his alpha channels working, it was kinda upsetting to rain on his parade when I could not find the cause of the problem.

That's perfectly normal behavior, Rhiannon. When you save to TGA, Photoshop will prompt you that the file will be saved as a copy. This is a safety feature which prevents you from destroying your layered work since the TGA format does not support layers. Were it to save as an original instead of a copy, the image would be instantly flattened, which is not what you want. You want to be able to preserve your layers in PSD format for archival purposes. TGA is just an output format, not an archive format.

Beyond that, tell your friend to make sure that he/she should always work in RGB mode, 8 bits per channel. As long as that's the case, then the option to select 24-bit or 32-bit depth for the image will be there at the time of save. Selecting 32 will include the alpha channel; selecting 24 will exclude it. Note that the bit depth dialog appears after you click OK on the regular save dialog, which confuses some people at first. Saving TGA's is a 2-click process in Photoshop, not a one-click like some other formats.