Certain images are downscaled when exporting despite setting to "full size"

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Level 1

11 points

Certain images are downscaled when exporting despite setting to "full size"

Very strange issue I am experiencing exporting JPEGs from my Photos library.

I exported a variety of photos from my library as JPEG - Max Quality - sRGB - Full Size.

While majority exported as expected, certain images (~20%) were downscaled during this process to maximum dimension of 1280px (from 4-5k).

The issue is consistent in that the same images will export correctly, and the same ones will export incorrectly (downscaled) if I repeat the process.

Reverting the image in Photos to the original seems to prevent the issue, so seems related to images that have edits applied (but not all).

Repairing the library did not resolve it.

Possibly related, all the images with an error receive an alphanumeric tag added to the "Special Instructions" ITPC field. This value is constant for any given image but varies between images.

Screenshot of the file metadata attached.

Possibly of interest, all the images with an error receive an alphanumeric tag added to the "Special Instructions" ITPC field, visible in file "Get Info". This value is constant for any given image but varies between images.

I have searched and searched but found nothing quite like this.

For reference and possibly related to the root cause, the library I am exporting from is an old Aperture library migrated to Photos in Catalina.

iMac 21.5" 4K, macOS 10.15

Posted on May 17, 2020 5:08 AM

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Answer 1

Best reply

léonie

Level 10

195,285 points

May 17, 2020 7:18 AM in response to David Duran1

If you have adjusted the Images in Aperture, the adjustments applied in Aperture will have been transferred as the current previews created in Aperture.

It will depend on the quality of the previews you created in Aperture. Your Aperture Preview preferences seem to have been 1280px for the size of the previews.

You need either to go back to Aperture to render the previews again in Aperture or to discard the adjustments applied in Aperture by reverting to the original.

Do you still have Aperture and the Aperture Library and can render the previews again? The process is described here: Migrate your Aperture library to the Photos app or Adobe Lightroom Classic - Apple Support

The big problem is, that you can run Aperture only on a Mac with macOS 10.14 or earlier. If you have still a Mac with Mojave try to rescue the Aperture adjustments there. If all fails, patch Aperture, so you can run it again on Catalina to render previews in a high quality: https://github.com/cormiertyshawn895/Retroactive/

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Answer 2

léonie

Level 10

195,285 points

May 17, 2020 9:33 AM in response to David Duran1

This shouldn’t be expected behavior though correct?

Unfortunately, it is the expected behaviour as described in the Support document for the migration (: Migrate your Aperture library to the Photos app or Adobe Lightroom Classic - Apple Support). Many Aperture adjustments cannot be recreated in Photos, because Photos does not support brushes and other nice tool. So we need to run Aperture to render full-resolution versions, because Photos simply has no way to render a full resolution image of the edited version. What Photos could do, however, when you are trying to export an image with a low resolution edited version, is warn you, that the edited version does not have the full resolution.

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Answer 3

David Duran1 Author

Level 1

11 points

May 17, 2020 7:25 AM in response to léonie

Thanks for the fast reply and it makes sense as the likely culprit.

This shouldn’t be expected behavior though correct?

A full res photo, adjusted in aperture then imported to Photos should retain:

the Original master untouched - this is ok
the Adjusted image in full res - problem here. I don’t know what Photos chooses to do re preview/thumbnail images but if the Exif info reports full res and I export it, I expect to get full res.

said another way, when I export from Photos it should take:

Original Master -> any preserved Adjustments -> My Export settings

Instead it seems to be doing this off the Preview images, and again, only in 20% of cases.

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Answer 4

David Duran1 Author

Level 1

11 points

May 17, 2020 7:27 AM in response to léonie

Btw - I do have original Aperture library preserved pre conversion to Photos, and can also work around this by reverting the images to Master in Photos (no need to dredge up Aperture on another machine).

it is highly manual though as I need to look at my exports, identify the 20% that failed, select them and revert, then reexport. Quite clunky.

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Answer 5

David Duran1 Author

Level 1

11 points

May 18, 2020 2:06 AM in response to léonie

Super clear and helpful. Thanks again.

I read that guidance a few times going back to last year, not sure how I missed the preview generation point.

Fortunately I do have an old Mac and retained the original Aperture library so should be able to redo through the migration process. Yay for backups!

Thanks again.

djd

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Answer 6

léonie

Level 10

195,285 points

May 18, 2020 2:09 AM in response to David Duran1

That's great, that you still have the backup on an older Mac. It would be impossible to recreate all Aperture edits with the tools in Photos.

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Certain images are downscaled when exporting despite setting to "full size"

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