alpha channel

[Madfox]

I'm getting intrigued on the way to use alpha channels on models to obtain partial transparance.

On the Extra-DVD there is a tutorial about it and while I'm following the example my results fail.

 

Point is that I can't save a *.TGA file with an alpha channel.

I'm using Photoshop 7.0 and when it transports the file,

I can only use *.TIF and *.PSD to implement the alpha channel.

Using *.TGA saves the file, but AM0.16 doesn't show it as an alpha channel.

 

Afterwards this "*.TGA" file doesn't have the alfa channel when I import it back to Photoshop.

 

I tried another graphic program CorelPainterIX, but there also I wasn't able to export a *.TGA file with alpha.

 

What can be the reason I can't import the right alpha channel with *.TGA?

Maybe because I use win32?

[johnl3d]

Not sure why you cannot get tga file with alpha channel you add the channel then save as tga file should prompt you about saving it with channel

[Madfox]

Indeed, that's why I'm so curious getting these errors

[robcat2075]

How to create a targa with proper alpha channel in Photoshop...

 

http://www.hash.com/two/RCHolmen/decalmakingMP4.mov

 

site for the Flaming pear plugins ("Free Plugins")

[robcat2075]

I'll also note that if you have created a Photoshop image with transparency (you can see the checkerboard background), saving to PNG will properly translate that into an alpha channel.

 

However i use TGAs because PNGs seem to have some crazy gamma adjustment inside them.

[Rodney]

This subject has come up from time to time as it relates to how Photoshop deals with the Alpha Channel.

I don't recall the specific answer as I'm mostly a Corel Photopaint user but I've recently taken to diving deeper into Photoshop as well.

 

Here's the specific 'problem' photoshop has historically had related to this:

 

http://www.adobe.com/support/downloads/detail.jsp?ftpID=1543

 

In essence what we have here is three channels:

 

Red

Green

Blue

 

And a fourth channel that is stored in file formats such as TGA and PNG as the Alpha Channel. This gives us:

 

Red

Green

Blue

Alpha

 

Some of us tend to use the term 'tranparency' instead of Alpha but there is something of a problem with this.

 

Circa version 7, Photoshop actually changed the way this Alpha channel was stored in that it saved the channel as transparency.

In effect this gives us five 'layers/channels':

 

Red

Green

Blue

Alpha

Transparency

 

The difference is that the last two can be the same but aren't the same depending on the implementation.

 

Note that there is a plugin at the linked site above that changes Photoshops behavior to that of how it handled Alpha Channels before.

 

 

Robert Holmen has a video tutorial that goes into some detail about the.... truly strange... way that Photoshop deals with Alpha *and* Transparency.

As it is a long lost tutorial, it is well worth reviewing:

 

http://www.hash.com/two/RCHolmen/decalmakingMP4.mov

 

 

Doh! Robert just beat me to posting a link to his movie while I was preparing this response.

[robcat2075]

Thank you, none-the-less, Rodney!

 

It wasn't really lost but quite an old one. I had to watch it be sure what was in it.

[Madfox]

Thanks for reply!

 

The tutorial was very usefull, as the FlamingPear plugins were.

Helps to understand what happens inside the pixel image.

 

Won't help me over the problem, though..,

My Painshop7.0 percist on keeping them saving without alpha.

I follewed the tutorial, but I end up the same as my second post.

A *.tga file, that glitches out of the import in Am16.

It's not possible to import *.pfd or *.tif files.

 

I downloade the PearlImageConverter and that made a *.tif a good *.tga file.

So it is possible, only then I have this huge logo on my image.

 

I wonder why Photoshop7.0 has this kinky mood.

[Fuchur]

Thanks for reply!

 

The tutorial was very usefull, as the FlamingPear plugins were.

Helps to understand what happens inside the pixel image.

 

Won't help me over the problem, though..,

My Painshop7.0 percist on keeping them saving without alpha.

I follewed the tutorial, but I end up the same as my second post.

A *.tga file, that glitches out of the import in Am16.

It's not possible to import *.pfd or *.tif files.

 

I downloade the PearlImageConverter and that made a *.tif a good *.tga file.

So it is possible, only then I have this huge logo on my image.

 

I wonder why Photoshop7.0 has this kinky mood.

 

try xnview or irvan view or try using png files.

 

See you

*Fuchur*

[robcat2075]

This TGA file has an alpha channel. It has green and white in the visible channels and a happy face in the alpha channel.

 

Tell me what loads in Photoshop. Resave it to a new targa and tell me what happens.

 

TestFace.tga

[Rodney]

You've brought back to memory one of many reasons why I've always preferred Corel Photopaint over Adobe Photoshop.

 

Assuming you are creating images from scratch, one thing you can do to fix many an image formatting issue is begin with a target image/format in place from the beginning.

For instance, since you know what type of image you want to use in A:M (Targa of a specific size etc.) you can create an 'empty canvas' by rendering out a file from A:M to draw upon in Photoshop or other program.

With a Targa image that already has the Alpha Channel/Transparency just as you need it Photoshop simply reads what is there and turns the process back over to you.

Then you don't have to be concerned with such things as, "Should this be 16bit image... 32bit?" etc. etc.

Just use the 'empty canvas' and you'll be starting from a known working point.

 

I've attached an 'empty' targa image that was rendered out of A:M.

If you import that into Photoshop and draw on it, then save it out as targa (and don't flatten the image in the process!) then the transparency of the Alpha Channel should work perfectly for you.

 

The whole idea of 'flattening' was strange to me as I was use to different terminology coming from Corel where they use the term 'combine'.

Ultimately it's the same thing with different words... but in the end if you wish to have parts of your image transparent you do not want to combine/flatten the images channels/layers if that will remove the transparency of the image.

Corel lets the user specify how to save targa files using 'normal' and 'enhanced' formats.

When desiring classic transparency for use in A:M that generally requires the file to be saved in 'enhanced' format.

Choosing the non-enhanced option will flatten/combine the Alpha Channel of the RGBA format into the alpha-channel-less (RGB) world.

emptytarga.tga

[Rodney]

I tested Robert's image and in the current Photoshop release there are two things I had to do to save Targa files with the Alpha Channel intact:

 

Upon saving the targa file:

1 Make sure the Alpha Channel checkbox is checked

2 Save to 32bit

 

Everything else I do on my end appears to flatten the image and strip the Alpha Channel out.

 

Attached are the two saved images side by side (from screen in A:M)

[Madfox]

@Fuchur - My AM16.0 doesn't import *.png files.

 

@Robocat2075 - In Photoshop7.0 the TestFace.tga file comes up as a RGBfile,

with no alpha channel as far as I can see.

In AM16.0 both work, only they appear different in Photoshop and CorelPaint.

 

@Rodney - If I use a *.tga output from the animation master the file has a RGB and three colours.

Maybe it's the misuse of the word transparant and alpha.

Photoshop has a way to add a alpha, but for some strange reason it is not what the files show.

Or my Photshop version is rubbish.

1 Make sure the Alpha Channel checkbox is checked

My second screen shows it's not possible.

[robcat2075]

that is loading into your photoshop differently than it loads into mine. When I load that targa i get just green and white in the RGB channels plus an alpha channel with the smiley face in it. No transparency in the working space like yours shows.

 

Rodney mentioned a plugin to make it revert to the old behavior. have you tried that?

 

 

And... you can't save to .PNG?

 

 

PNG is available in v16. It should be importable.

[Madfox]

Thanks for advice!

 

My version of Photoshop7.0 is rather old.

I don't know what excactly happens, the upper left is Photoshop, the righ one CorelPaintIX.

It looks as it is something with import compatibility.

I can import *.png files in Am, only Photoshop won't export them.

I tried the plugins, only PearlMountain gave me so much errors at start I won't try.

 

I asked this subject before, as it fainted me on the tutorial.

Then when I really tried to solve it all other graphic progs (gimp) gave different outs.

So I'll keep it on the fact I can use a transparant layer on a model.

 

Masks, Layers, transparants, alpha's, it's starts dazzling me.

[johnl3d]

Can you post a picture and indicate what part you want transparent ?

[NancyGormezano]

the upper left is Photoshop, the righ one CorelPaintIX.

It looks as it is something with import compatibility.

 

I definitely think there is something wrong with your system's ability to read tga files (maybe just those tga files with an alpha channel?). I don't think it's only a problem with photoshop.

 

Your Corel painter IX does not look right either. All I did was OPEN (NOT import) Robert's file and I get an alpha channel in my Painter IX

I also had an old copy of photoshop 6.01 (do not have 7). The alpha channel shows up as well.

[Madfox]

@jhonl3d - I can use simple 2channel transparant layers to create a decal.

I was just wondering why I'm getting these parms for the same programs.

 

@Germenzano - I think you're right.

Obvious I can't see what's wrong with the system.

Could it be win32, can't believe it either.

 

I looked at the preferences but can't find anything.

Seems my computer has an alpha fright.

 

Thanks for your support.

[robcat2075]

What is the "Save as a copy" for?

[robcat2075]

I find this on an Adobe forum...

 

In 7.0 Adobe changed the Targa export to use Photoshop's own transparency as the Targa's alpha channel. This would actually be quite a useful option to have, and is how PNGs are saved, so I can see why. But then they realised they'd messed up compatibility and changed it back in 7.0.1. We know about it and we're using 7.0.1.

 

Which Photoshop 7 are you using?

 

If you are on 7.0, have you tried the plugin Rodney mentioned?

[NancyGormezano]

@Germenzano - I think you're right.

Obvious I can't see what's wrong with the system.

Could it be win32, can't believe it either.

 

I looked at the preferences but can't find anything.

Seems my computer has an alpha fright.

 

I use win xp pro 32. Maybe there is some common windows file? dll? filter? that is used by both photoshop and painter to read TGA files that perhaps is corrupted? I don't know enough about windows OS to say where that might be.

 

I see that AM uses something called tga.iio

[Madfox]

Searching the web I find all kind of info about tga file errors.

I tried the update for Photoshop, but it doesn't "see" my directory.

 

All by all I begin to believe it is something with my system.

 

It it the same kind of error I can't load 32 meaures in my midistudio.

Then I get abused because it isn't a 64 bit system.

 

I have to live with it.

[robcat2075]

Have your tried uninstalling and reinstalling Photoshop?

 

(Make sure you still know your complete serial # before you uninstall)

[Fuchur]

Searching the web I find all kind of info about tga file errors.

I tried the update for Photoshop, but it doesn't "see" my directory.

 

All by all I begin to believe it is something with my system.

 

It it the same kind of error I can't load 32 meaures in my midistudio.

Then I get abused because it isn't a 64 bit system.

 

I have to live with it.

 

You may want to use PNGs (I hope those will work).

 

See you

*Fuchur*

[Rodney]

There is an error on screen in the first image you posted (in your second post).

It says something about saving a copy of the image.

If you are trying to save over the top of the same image that may be what that means.

 

But I think you should perhaps off check that option to see if it activates the option for Alpha Channels.

I note that the Alpha Channel option is greyed out and of course no alpha channel is what you are getting.

 

Here's the image for reference:

 

[Fuchur]

There is an error on screen in the first image you posted (in your second post).

It says something about saving a copy of the image.

If you are trying to save over the top of the same image that may be what that means.

 

But I think you should perhaps off check that option to see if it activates the option for Alpha Channels.

I note that the Alpha Channel option is greyed out and of course no alpha channel is what you are getting.

 

Here's the image for reference:

 

 

Are you asked if you want to save 16bit, 24bit or 32bit-version?

I am only familar with Photoshop CS (I think v8) and up where it worked always as it should for me.

 

See you

*Fuchur*

[NancyGormezano]

Searching the web I find all kind of info about tga file errors.

I tried the update for Photoshop, but it doesn't "see" my directory.

 

All by all I begin to believe it is something with my system.

 

It it the same kind of error I can't load 32 meaures in my midistudio.

Then I get abused because it isn't a 64 bit system.

 

I have to live with it.

 

I too searched the web and came upon this thread

 

http://forums.cgsociety.org/archive/index.php/t-49256.html

 

One of the solutions proposed was this

Two options.

 

1) Get the photoshop 7 upgrade to 7.1 from Adobe's site.

 

2) You upgraded to 7, so you still have an older version right? Copy the Inport/Export plugin for TARGA from your older version, and replace the one in PS7 with that one.

 

Either way, this will fix the problem.

 

Reason for the problem:

 

Adobe, after 6 versions of using the Incorrect version of the TGA file, along with almost everyone else, deided it would be a good idea to impliment the format the way it was originally intended. They neglected to factor in that after 6 versions of photoshop, various corel draw's, painters and Paint shop pro's that people might have more uses for the "mutant" TGA's than the original format.

 

Smart thinking Adobe. But at least they addressed it in the 7.1 patch.

 

I have photoshop 6.01 so I've uploaded a zip file containing Targa.8BX from my system, found under program files/adobe/photoshop 6.0/Plug-Ins/FileFormats folder. Perhaps try this and see if that helps? This could explain why Corel painter isn't working either.

Targa.zip

[pixelplucker]

I don't bother with Targas anymore since Windows doesn't natively preview them in icon view. I have converted all my textures to png if they need an alpha. This is the most compatible format with alpha support.

 

I do wish AM supported PSD files with layers. Be so nice to be able to have a single file and call a particular layer for a channel, ie: layer 1 difuse, layer 2 bump map etc.

[robcat2075]

I do wish AM supported PSD files with layers. Be so nice to be able to have a single file and call a particular layer for a channel, ie: layer 1 difuse, layer 2 bump map etc.

 

I've wondered about that too. Have you made a feature request out of that?

 

I'm not sure how many user have Photoshop however, and how well the other paint apps conform to the proper PSD format. I don't know if it's a can of worms or not.

[Fuchur]

I do wish AM supported PSD files with layers. Be so nice to be able to have a single file and call a particular layer for a channel, ie: layer 1 difuse, layer 2 bump map etc.

 

I've wondered about that too. Have you made a feature request out of that?

 

I'm not sure how many user have Photoshop however, and how well the other paint apps conform to the proper PSD format. I don't know if it's a can of worms or not.

 

The biggest drawback is: It is a propheritery format. Other than that: I can't see why you should not make a feature request for it. We will see what happens.

 

Till then you may want to try this:

http://games.greggman.com/game/tga_thumbnails_for_windows/

 

See you

*Fuchur*

[robcat2075]

I guess what I've learned is that the TGA format I've been using all these years was wrong, but I like being wrong and i don't want to be right.

[Fuchur]

I guess what I've learned is that the TGA format I've been using all these years was wrong, but I like being wrong and i don't want to be right.

 

TGAs are fine... PNGs have drawbacks (like not being able to reconstruct pixels which are transparent which can be done with tgas) but are widly supported.

Both are fine, but TGAs are actually the better format for postprocessing because of that.

 

See you

*Fuchur*