One of the larger changes in iOS 11 was Apple's adoption of the new High Efficiency Image Format (HEIF) standard for photos. While the format is significantly more efficient when it comes to storage space, it's not yet widely supported, meaning you may run into problems when you want to use pictures taken with your iPhone (or iPad) elsewhere.
When you transfer a HEIF image from your iPhone to your computer (this also happens if you back up your iPhone photos to Dropbox or Google Photos), instead of the typical JPG extension with a thumbnail preview, you may be met with a HEIC (HEIC is the container for HEIF and can contain multiple images) image instead.
You won't be able to open the image in any of your typical photo viewers or editors. Your only options are to convert images or avoid HEIC until the new standard is more widely supported. Here's how.
Tweak your iPhone settings
There are two things you can do on the iPhone (or iPad) itself to avoid the HEIF/HEIC conundrum.
For starters, you can avoid taking HEIC images altogether and revert back to JPEG images. This will take up more storage on your phone, but will make transferring and using the images more seamless. To revert to storing new pictures as JPEGs, go to Settings > Camera > Formats and select Most Compatible.
The other option is to convert images from HEIC to JPG on the fly when you transfer them from your iPhone to a Mac or PC. Go to Settings > Photos and look for Transfer to Mac or PC at the very bottom. Choose Automatic to have images and videos automatically convert to a compatible format before transferring.
The latter option is a good compromise. It saves storage space on your phone while transferring compatible images to your computer. However, if you're uploading your photos to a cloud service, they will still be uploaded as HEIC images. When you download them to your computer, you will once again run into the compatibility problem.
Convert to JPG
The first line of defense is having a solid image converter on hand. The problem is, not all image converters have been updated to include support for HEIF.
To use iMazing HEIC Converter, download and install the program. Then drag and drop all the HEIC images into the converter. Select whether you want to convert the images to JPG or PNG, uncheck the box next to Keep EXIF data if you don't want to remove it, then drag the slider next to Quality to select how much quality you want the converter to preserve. At 95 percent, most of the images I converted to JPG were double the size of the same HEIC image.
How to open HEIC in Windows Photo Viewer
For Windows users, there is at least one more option. The company behind CopyTrans HEIC for Windows., an alternative backup utility for iPhones, iPads and iPods, created a plugin that brings native support for HEIC to Windows. It's aptly named
After you download and install the program, you will be able to view HEIC images within Windows Photo Viewer. This won't allow you to open it in just any program, unfortunately. Photoshop and even Paint will throw an error. But at least you can view the images on your Windows machine.
For now and until HEIC sees more widespread support, it's probably best to keep both CopyTrans HEIC and iMazing HEIC Converter on hand.