I know very well the Pro's and Contra's of PNG and JPEG but if I already have an image that is compressed it's not normal that I get out something in the same quality, only the file size is 10x bigger... How is some on in this project imaging that users would like to add a gallery to their web sites with for example 15pix each of them 200kb - JPEG size... I will get and SWF file that nobody will be able to load because it's 30mb ... I'm sorry, but usually I can compress images very well in SWF file's ... example www.losynskiy.de - the whole site is 1,5mb with 33 Images ...
So another solution and answer is needed ..
Yeah, come on, it's evidently a bug! Nobody is gonna make slideshows with pictures without transparency in PNG format - this format was just not made for it. If I'm importing JPG then exporting it as PNG won't make the quality better.
From what I've seen ROME already has possibility to export JPG images through Output->Output Channels->File Export->JPG (but only as seperate composition elements, not as a part of a whole project)