render layers - visibility check and file format

[andy.engelkemier]

I'd rather use tiff. Photoshop trashes data inside png files, so I'd rather not use them. That's mostly a personal preference though.

It would be nice if there was a simple check of some sort though. I did a render region, and still wanted render layers. Some of the layers are outside of the region, so it basically renders a blank image for those layers. That seems rather unnecessary. It could probably just do something like, check to see if the image it is about to save has 100% transparency. If yes, just don't save it.

This is low priority for sure. But it might be an easy one to check off the list.
Something that might be nicer to have is to save the files instead into layers tiff files, or layered PSD. Both would accomplish the same thing really. That just keeps me from having to open up bridge and running the files to photoshop layers script.