The Preview app on MacOS has a ton of useful features, from annotating images to converting file formats. Recently I had a bunch on .png screenshots that I needed to convert to jpegs. While I was aware you can Export an image file in Preview and save it in any other supported format, I was looking for a quicker way to bulk convert a large number of files.
Turns out, as explained in this article, if you select a group of images in Finder and double-click one of them to open them all in one go, you can select all the images from their thumbnails on the left:
… then from File click ‘Export Selected’. From the dialog chosoe where to write the converted files, and press Options button to change the file format. Done!