...the two Apple Compressed File (HEIF) pictures...size was 1.2GB. Assuming that if I had used JPEG settings, I would have gotten a similar size to the above picture of 3.4GB..
Two still images total 1.2 GIGABYTES? That's just crazy!
I work in Photoshop literally ever day. I have prepared tens of thousands of images for publication in this magazine, other magazines and for a book I'm about to publish. A FULL PAGE image at 300 dpi, in CMYK color format is a tif image of 30 to 40 Megabytes. To say it another way, that's .03 to .04 Gigabytes for a full page, 8.5" x11" image. A high quality jpg image (a compressed format) is in the 8 to 10 megabyte range, which is .008 to .01 Gigabytes.
How in the world do you get 1.2 GIGABYTES in only two still images? Even worse, how to you get to 3.4 Gigs for two jpg images!
Something is drastically wrong here.