.exr file import - alpha question

[RobWu]

Hi Guys!

It's great to see Photo can work with .exr files out of the gate :)

In my line of work (3D), I work with .exr files a lot. This can be single channel (layer) files, or .exr files containing multiple channels (layers).

If I open a single channel .exr in AP, I get a RGB layer and a separate alpha layer.
This could be helpful, if only the RGB layer had a 'cut out', so no black bg where the alpha should be.
It's the same for .exr files with multiple channels, have all channels imported with the alpha being transparant on each layer if it's there.

This is a plugin I use for PS that does more or less the same thing, but has some nice additonal options when importing: http://www.exr-io.com/
Especially the option to split (or not) the alpha channel, and the option to add alpha to all layers when importing is extremely useful imho.

I would be nice to see this behavior to change in the future, as it would eliminate one step when the 3D object has no background.
PS can import with a transparant bg, but looses the extra matte layer (after years of nagging at Adobe btw.....)
 

And thanks for releasing Photo to Windows!! :)

 

rob

 

edit: I cannot seem to upload a file, so here's a linked file ;)

 

[James Ritson]

Hey Rob, there are currently three OpenEXR import options on the Preferences>Colour dialog which allow you to control alpha premultiplication, post-division and zero-alpha handling - have you checked the video tutorials? OpenEXR Import Options covers them.

 

It sounds like alpha association (premultiplies alpha into the RGB layer) is halfway to what you're after? From what you've written I gather the option to have alpha as a separate layer but also premultiplied on the RGB layer would be useful?

 

Bear in mind that there will be further work done on OpenEXR import/export in the future, especially to cover idiosyncrasies with layer naming conventions that differ from the OpenEXR spec. (Cinema4D seems to be one such example here)

 

Hope that helps!

[RobWu]

Hi James,

Thanks for the quick reply.

I missed those options on exr import completely, and the alpha association is what I was looking for. (Still getting comfy with the application ;) )
This association option will create layers will alpha as I want in most cases.

A separate B/W layer with just the alpha information for additonal tweaking could be a nice option to have too.

Just a note, it's probably the alpha multiplication issue per layer, but here's a hard 1 px offset in the alpha border.
If I have a ID color channel as well, you can clearly see a 1px border black border around a color mask.

If you select a color, there's now a 1px border 'missing' in the selection for a mask. You can expand the selection of course, but it was something I noticed.

The exr-io plugin has a transparant 1px border, so it's less apparant when selecting a mask color, or interfering with the selection.
But in both applications, with all the layers added, there's a slight shift of the edges as well compared to the beauty layer. It's the nature of the beast I guess ;)


cheers!

 

rob