Photos won’t export full resolution

Well, I may have found the solution, but I have no understanding of what or why. I created a new library and just imported a single jpg image from my iPhone 6 and it showed full resolution and exported as full resolution. I then imported a single HEIC file and did the same drag export and it retained resolution as well. I am in the process of importing the 1,912 images into the new "test Library" to see if the results hold. If so, then it was something in the library... but why? how? no clue the cause.... Let's see what happens here in a few moments....

It appears to have been the library itself... why? I have no clue, but the problem appears to be solved.

This time I imported the images from a folder of all the images. This folder was created by importing from a folder rather than the cameras. Perhaps importing from the iPhones contributed to the problem? Although it doesn't make sense. IF that is what I did, I probably followed this workflow. Create a library, import the photos I wanted from both cameras. I wanted those same files in another folder, so I opened the "package" Photos library by right clicking and option dragging the Masters folder to the desktop... This would not affect the library, and all the files in the new folder are still full resolution. When I recreated the library today, I imported from that folder rather than the iPhones. That's the only difference, but I don't see a cause and effect. Also, if I duplicated the Masters folder, I captured all the resolution of the original files, so the files should have been fine. Somehow that library was locked into an export to jpg with a low resolution.... let's see if I can export an original HEIC file to desktop now. Not sure if I can export original files, but at least I have the resolution I was after.

Yes I can... now a full resolution HEIC file shows up on my desktop. Not sure the bug, but creating a whole new library seems to have been the solution. I'm not sure if that other library can be fixed somewhere, but I will keep it and see if anyone has anything they want me to try, but my suggestion for similar problems is to create a new library and just import everything again. I used to have one massive library, but I have learned to work with multiple smaller libraries when needed. In this case I import to smaller libraries on my laptop, and then later import into a master library on my office computer.

Well, that was interesting.... I deleted the last photo, imported it again, and it exported at full resolution. The photo prior to the last I exported at it was still at the lower resolution. I know both files have the same resolution based on "information" on the images, but they export differently. I suppose I could have deleted the preferences file in an attempt to fix the problem, but since the preferences are app specific, it probably is not a preferences problem because it would have affected both my new library I created, and it would have affected my last experiment. The last image worked fine, but all the others are still the same. That wouldn't be a preferences thing I don't believe. It was an interesting thought however. Hmmm.

3088 × 2320 is the native resolution of the heic file. When I drag it to the desktop it converts to a jpg file with 1026 × 762 resolution.

If I do an option drag of the image I get an error message on my MacBook Pro Mid 2012 running High Sierra 10.13.6. The phone IOS is 12.x. I get the following error message and nothing copies.

"Export Complete with Errors

0 (of1) files have been exported to:

Desktop

The export operation failed to create a file for the photo identified below:

File name IMG_3214.HEIC

Errors The file "" couldn't be opened because there is no such file.

If I use "export" I choose jpeg, maximum quality, most compatible and Full Size. The file exports to desktop with the following file size. 1026 × 762

If I export that image as an unmodified original in the export dialog I get the same error message as above about no such file.

Somewhere when I drag an image out that is HEIC, it is being translated into a jpeg with constraints that I am not applying. I can't even set my own "Custom" export options as it will still export as 1026x762. For instance, in Cusomt, I will set the Max Width at 2320 to match the vertical image.... and you guessed it, 1026x762.

These photos are from my girlfriends iPhone 10. I have png files I have captured from the desktop that I can control and export at full size by just dragging and dropping, plus I have photos from a Canon 50D that I can drag the full size images as well. It all seems to center around the HEIC format, and whatever it is being converted by, but I can find nothing on the problem.

I think my response to the other post covers your question. It would seem intuitive enough to just change the export to "Full Size" and that should cover it.... I even tried to just use "Large" in the hopes that it would be larger than the 1026x762, but instead it was 513 × 381, which is nothing resembling "large" by any means.

Bottom line, what is overriding Photos settings that is doing the converting of the HEIC images? Something is overriding the Photos settings, but I can't figure it out. Restarted the computer, the app, zapped pram. Nothing is changing the end result.

Well, ****, I had a thought in my description that perhaps MY photos from my iPhone 6 would work. They came in as jpg files, not HEIC. The original resolution of the jpg is 3024 × 4032, but when I drag to the desktop the same thing happens... it is converted to 768x1024. Again, downsized against my will?

I think I will create a whole new library and see if the library is somehow corrupt?? Wide open for suggestions!!