Image Capture HEIF Conversion Padding
If you connect an iPhone or iPad to your Mac, and use Image Capture to transfer the photos you took with the device to the Mac, you have the option to convert the HEIC photos taken by iOS to more standard JPG files. This requires you to uncheck the “Keep Originals” option in the settings for that iOS device, as shown here.
Apples Image Capture will then happily convert the HEIF files to JPG format for you, when they are copied to your Mac.
But what is also does is to add 1.5 MB of totally empty data to every single photo file it creates!
That’s a huge percentage of the total file size.
Update (2020-05-06): Tim Hardwick:
Today, we’re hearing that the bug in macOS 10.14.6 and later is a lot more extensive than was initially believed.
[…]
For users with large existing photo libraries, Doerner has suggested using a new beta version of the third-party utility Graphic Converter, which includes an option to remove the unwanted empty data from the JPEG files.
On investigation, I found that all of my photos imported from iPhone to Mac going back to October 2017 have this giant chunk of empty data.
The current Retrobatch beta has a node for truncating empty data from JPEG files suffering from the Image Capture iOS transfer bug[…]
I suspect very few people at Apple use anything other than Photos to transfer images from their iPhones, and it shows. For those who use any other application, however, this is a the kind of relatively minor bug that has lasting consequence.
Update (2020-08-07): Retrobatch:
Oh, and 1.4.2 introduces a new new “Truncate JPEG Data” node, which will remove empty data at the end of JPEG files which could be introduced when transferring files off of an iOS device.
