In maya 8.5 when i use to render a targa image with transparency, the alpha was already applied to the rendered image with no anoying black background when opened in Photoshop.(just the PS default cheker background).

Now In maya 2008/2009 when saving an image in Targa format, the image is saved with a black background and the alpha of the image is stored in the alpha channel.

How can i save a targa with the alpha apllied directly in the image (no black background) in maya 2008/9?

that really has little to do with Maya as much as it has to do with Photoshop. If you render to PNG it will open with in PS the way that you want it to

i got a problem with the same issue. when i open a tif or exr in photoshop the alpha is gone and the rgblayer is clipped by the alpha. opening the image in e.g. nuke works fine with a alphachannel. how can i prevent photoshop from doing that ?

using the png format dixed my problem.

Well it as more to do with the fact that this si the desired effect (alpha is just a channel on most formats nothing says it has anything to do with transparency, png being the ONLY format that explicitly says alpha must be transparency out there). But just load the alpha channel unlock the background layer invert the selection delete and run remove black matting

i didn't really get that. i mean if i open it in a other program and save as tiff again and open in photoshop everything is fine, so it must have to do with the tif format output of mental ray or something.

Some highend compositing hardware (such as flame, inferno) needs separated alpha (matte) for their compositing purposes, so they can use the RGB or the Matte.
I think thats why 2008 & 2009 separate teh RGB and Alpha Channel (in one file), may be for their Highend Autodesk Stuff.

PNG sould works fine for direct matte.

Well adobe tied to make this automatical. But they got killed for it.

See thing is alpha might not just be alpha and once you let the computer get into the guessing game then the datas going to go wonky. (the greatest possible illustration of this is excel and its time format suddenly is nolonger time because excell thinks it knows better than you. It leads to surprising problems to people that need to rely on what things are. Like for me you just can not print python in pdf file with indesign without crapping things up for copy pasters). Its not a big issue to you to fix but unfixing when photo shop goes wrong is a BIG problem taht can kill your ability to use photoshop.

For example the image might not be colors at all it might be U V and NX NY data. this is perfectly valid if you intend to use the mgae for data processing.

But mostly its about what the standards say. if the standards say that its transparency then go for it if they say its jut a channel among others then it may be just that.

So if i tell you thet you can park green cars in this spot or ill bill you otherwise. Then you put a lime green car there you will hold me for my word.