If I’m using ViewCaptureToFile, select Transparent Background, click Ok, and then in Save as type I select .jpg, then save, the result is a .png file.
(I understand that transparent background isn’t supported by jpg, but I think the Save as type options should reflect what file type will be created.)
Well, the argument cuts both ways… if you ask for transparent, it should make transparent, so jpeg is out…
I believe that earlier versions would do what you are asking (create a jpeg without transparency), but it was changed based on user requests here.
Hi Peter -
As Mitch says, it looks like this used to behave differently at some point but we’ve had the request to change this again on the list for a while now…
→ RH-64908 ViewCaptureToFile: Transparent background forces png format
-wim
png’s are better than jpg’s 
Note: implementing RH-42926 would “solve” this by not offering incompatible file formats
Works for me…
RH-64908 is fixed in Rhino 8 Service Release 9