Alpha Channel (dumb question)

[AJLynn]

Supposing I do a mental ray render in Max 2009 and save a .EXR file with alpha channel. My expectation would be that when I load it in Photoshop I get the image, and in the channels there is an Alpha. Instead the image has transparent bits and the Alpha is not show, and the background that was Alpha'ed out is nowhere to be found.

 

I assume it's there because if I do the same thing but with a PNG file, the same behavior happens in Photoshop but Windows displays the image with the background.

 

So how do I make this work the way I think it should work?

[RobNJ73]

I usually render images out to .TGAs with the alpha split so I have the black and white mask already created that I can either plug into opacity channels, or use as a starting point for another mask.

 

As far as .EXR goes though, I'm not sure... do you need the part of the image that was alpha'd out, or is this more a case of trying to understand why this is happening?

[AJLynn]

Both. Suppose I just want the alpha'ed part on a layer at the bottom - that sort of thing should be easy...

[mattclinch]

EXR format sees alpha channels as a 'transparency from alpha' rather than a standalone alpha. IMO one of the downsides of EXR.

 

TGA it.

[AJLynn]

Does TGA support high dynamic range?

[gfa2]

Andrew are you using CS3? It doesn't read the alpha correctly in EXR's. If you take the Photoshop EXR plugin file from CS2 or CS and replace CS3's version, Photoshop wil behave the way you are expecting.

[AJLynn]

Thanks, I'll try that.

[SandmanNinja]

Wow - good news! Can you please elaborate on how to bring that file in from an earlier version?

 

I went from CS1 to CS3 - can this still work?

[gfa2]

Wow - good news! Can you please elaborate on how to bring that file in from an earlier version?

 

I went from CS1 to CS3 - can this still work?

 

You need to replace the "OpenEXR.8BI" that CS3 installed with the same file but the CS1 version.

[SandmanNinja]

Thank you!