Automatically convert images in Photos.app In Photos.app, I have a lot of large png files that I would like to convert to jpeg files. Can I somehow convert them all automatically and keep all the metadata in the process?
You can select all the png files in your photo and then under the File menu select Export. The top option will be to Export x items where x is the number of png files you selected. Select that option and a new pane appears where you can set the type as jpeg. See pane below.



I'm not positive this saves the metadata so I advise you to run this on one image and see if it works.