Which image format works best?

I'm just starting out with Shake, and I'm trying to zero in on the best format for Photoshop images to bring into composites. I use a lot of "cut outs", or elements with the background removed. I've used PNG images in Final Cut Express & Pro. There's a different result bringing them into Shake, though. Edges that appeared fully trimmed in Photoshop (I use elements 6, by the way, not the full CS3)still have a lot of rough edges in Shake.

It's as if all the finer erase strokes made in Elements are being ignored, with thick, ugly fringe along the edges and around hair. I would prefer to refine the images before bringing them in, but if I can't expect to see the same edges after importing it's pointless.

Is there an image format that translates between Elements 6 and Shake with better integrity? I'd like to know early on so I don't waste any time preparing images in the wrong format.

Any tips on creating a clean, solid image that looks the same across the whole process would be appreciated.

I tried a 3 layer .psd file last night as a test, with the top layer being the cut out element, imported as a Photoshop file from the drop down menu. The fringe is there.

It's frustrating, because I'm usually very critical about going over the edges and cleaning them up. Every now and then the opacity on the eraser gets turned down and it leaves a haze that's almost impossible to see against the background checkerboard, maybe it ends up more opaque once imported? I'll have to check the original image file to see if I left a haze behind.

Usually I prepare these cut outs by making a copy layer, then I erase
the background with a combination of the magic eraser, regular eraser, and lasso then command+X for the outer areas. Once I'm satisfied with the outline, I trash all the other layers (if I flatten it fills the background in with white). I've been saving these as PNG files. This usually works in iMovie, FCE & FCP for superimposing. I had a strange case with Motion recently where it actually imported the inverted area from what I intended, part of a layer I had deleted (or thought I had). I guess Photoshop files carry the ghosts of layers thought to be long gone. I'm sure I'll find a formula that's trustworthy, I'm not such a fan of carefully trimming out images that I want to keep repeating it on the same images.

Hmn. Troublesome. Whichever way I import, there's often a big difference in how cleaned up an image is. I like being able to bring in a PS file with it's layers accessible, but that raggedy fringe won't do.

I have a workaround already, though. It's a whole extra step I'd rather not have to make, but if I take the layer intended to be the cutout with empty space, and instead merge it with a solid green layer, I can use a keyer on it and get a cleaner image to superimpose. It's limiting though, because now I have to consider the colors in the image, and whether there's any green in it, and if so what color to use.
Things I wouldn't need to worry about if the image that looks fine in Photoshop carried over in Shake.
I may still get to the bottom of this, but at least there's a backup plan.

On the other hand, my first real test of keying video worked really well. A very uneven green in the original shot. Final Cut Pro's keyers couldn't clear out the dark corners and fringe. Same shot in Shake, I apply Keylight, click once in the mid-green and instant perfect key! Through a 1/4 angle eyeglass frame, hair, and even motion blur, it didn't miss a beat. Amazing difference, If it does that well with a poorly lit green background, it can't miss with a good one!

I wasn't sure when I got Final Cut Studio whether I would have any need for Shake, but took a chance anyway. I'm already glad I did, even if it has been orphaned. It has already distinguished itself alongside all the FCS apps as "key" element. I hope Apple doesn't start breaking it's compatibility with future OS upgrades, unless it's successor is in the same price range (doubtful), I'll be using it for a while.