I have my iPhone set to capture HEIC, and Dropbox client set to Save HEIC Photos As JPG.
If you take a "Portrait Mode" photo on the iPhone in HEIC, and have Dropbox convert this to JPG, the JPG is unviewable on a Mac running Sierra.
Non "Portrait Mode" photos are viewable fine on Sierra, and Portrait Mode photos that can't be viewed on Sierra, can be viewed on High Sierra.
NOTE: Portrait Mode is not the orientation of the phone, but a special mode that tries to create fake Bokeh by blurring the background through software.
iPhone 7+ iOS 11.0.2
Dropbox for iOS v66.2.8
macOS Sierra v10.12.6
macOS High Sierra v10.13
Dropbox for Mac v35.4.20
Please see Screenshots:
Not to hijack this thread, but I don't have the HEIC option in the Dropbox app (iPhone SE, iOS 11.0.2, latest Dropbox app). This is odd, as I also have a different (related?) problem where I can't enable background uploading and my videos aren't uploading for which I have a ticket open.
Just curious if you have High Efficiency or Most Compatible selected in the iOS Native Camera option? I don't think it matters, since the Dropbox app shows the option either way I set it on the iPhone 7+.
I also noticed another option that is very interesting, under Settings > Photos > Transfer to Mac or PC:
I created a Dropbox support ticket and directed them to this thread. Hoping they are aware of the issue and are working on it.
You can change the format back to JPG but if you've already used the HEIC format, the only thing you can do is convert your images. There are few converters already and I found this Free HEIC Converter to JPG. This works perfectly as I was able to change the format of my images without losing the quality of my pics. It's free and does not require installing additional software as its an online tool.
So I have a file with a .jpg extension that cannot be opened Sierra but can on High Sierra.
Let's assume it is really a .heic file but has an incorrect .jpg extension.
Now I change it to .heic as you suggest.
What exactly would the next steps be? And how would those steps prove your theory?
There are no next steps. It was simply a suggestion for when you come across a JPG or HEIC file that wasn't recognized (by the file's extension) and couldn't be opened. Changing the extension may allow you to open the file because the extension would then match the file type and the operating system would then know how to handle the file.
Going back to look at it, the Dropbox iOS app was uploading HEIC files and renaming them to JPG, but not actually converting them. Changing the file's entension from JPG to HEIC allowed the file to be opened normally. No data was being lost. This issue was corrected.