Exporting vs "Exporting unmodified original" in Photos

The "original" is the original imported photo _without_ any added edits to the image or to its metadata (date, location, caption, keywords etc). You can export the edited metadata with the IPTC option and join that sidecar file to the image with tools like Graphic Converter or exiftool.

The "regular" export obeys the quality setting when _re-encoding_ the exported photo so it will have generation loss and might well be larger in MB than the original. It should contain all the edits and added metadata (although AFAIR in Big Sur as a bug currently only in .tif?).

I prefer the original quality although I wish there was an option to export edited metadata with the image.

The two exported images appear to be equal in resolution (4032 x 3024 pixels, taken on an iPhone 11). However, the "regular" export takes up more space (9 MB) than the exact same resolution image from the unmodified original export (5 MB).

It's about compression.

You're shooting Jpeg, and oddly, Jpeg is not a graphic format, it's a compression format. When you take a photo it's processed and saved as a Jpeg by your camera/phone. But that jpeg is just a container. Within it is the photograph, all 4032 x 3024 pixels of it. When you view the photograph the actual process is that the Jpeg is decompressed and opened so you can see the image within.

Now you import that 5mb jpeg into Photos (or indeed any photo manager) and then export it again. Export the unmodified original and you get exactly that - a copy of your 5mb file.

But if you export a version... that is, use the export command and choose to export as a Jpeg what happens is that Photos makes a new file, puts a copy of the photograph into it and exports that. As the new file is a Jpeg there is also compression applied. In the export dialogue that is controlled by the 'Quality' setting. Export at the highest quality and you get the largest file size because that's the least compression. Lowest quality you get the smallest file size because that's the most compressed.

So how do you get a file larger than the original? Because Photos is applying less compression to the photograph than your camera/phone did. Same photograph, different amounts of compression in saving as a jpeg.

That's what's going on there.

When you export the edits version with "File > export > ... images", you have four options for the amount of JPEG compression. You will see them, when you click the disclosure arrow to the right of "Photo Kind: JPEG".

• The option "Maximum" will result in no compression at all, and the file size will usually be larger than the original JPEG created by the camera.
• The option "High" will result in a reasonable compression, if the original has already have a slight compression applied.