Everyone knows JPEG. This image format is recognized by all programs and apps that can display images as well as by web services and web pages and can be passed on from one device to another without any problems. But what is HEIF? Also an image format, but more modern and efficient than JPEG. Since iPhone 7 and iOS 11, this format can be used by the camera to save the photos, as well as on the more recent iPads. The Mac has been able to handle the image format since macOS High Sierra. Communication problems can occur with other operating systems and on the web.
HEIF (pronounced “Hief”) stands for High Efficiency Image File Format. The format is not an Apple invention, but an industry standard developed by the Moving Picture Experts Group (MPEG) (ISO / IEC 23008-12). One of the goals was to develop a flexible image format that not only saves single images, but also image sequences and animations, and even both in one file, such as the live photos from the iPhone camera. In addition, depth information, transparencies (alpha channels) and image sections (cropping) can be stored in a HEIF file. So HEIF is not a monolithic file format, but a container that can contain various objects and information. But that is only one side of the coin. Because in addition to a more flexible file format, less space should also be used than with the JPEG format, with the same image quality.
In order to transmit high-resolution videos over the Internet or to save them on a data carrier, a good compression process (codec) is necessary to reduce the amount of data as much as possible without sacrificing quality. H.264 / MPEG-4 is widely used today. The codec, also an industry standard, is used by Blu Ray, among others. High Efficiency Video Coding (HEVC) or H.265 has been a more efficient compression method for several years. It can save between 25 percent and 50 percent of the data compared to H.264. (A successor with the designation H.266 or Versatile Video Coding (VVC) has recently been in the starting blocks.) HVEC has been using Apple since 2017 not only for the videos recorded with the iPhone and iPad, but also for the photos can be compressed more efficiently than with JPEG. Another advantage of the HEIF image format is that you can use different compression methods.
If you look at the information on the Mac on the photos that were taken with an iPhone or iPad and that use the new image format, they do not have the file extension (suffix) .heif, as might be expected, but .heic. This suffix is used when an image uses HEIF as the file format and HVEC as the codec for compression. This is the case with recordings with the iPhone and the iPad. If you display the file type in the Finder in the list view, the name is “HEIF-Image”.
The H.265 codec is also used for videos on iPhone and iPad, but Apple uses the QuickTime format as a file format, as can be recognized by the .mov suffix. Like HEIF, the format is a container that can contain differently compressed videos. At first glance, it is not clear whether a video uses H.264 or H.265 as codec. You can get this information quickly in the Finder via the information window of the respective video file. There you can read either H.264 or HVEC under “Codecs”. The same applies to the information window in photos.
If “Formats> High Efficiency” is selected in the camera settings on the iPhone or iPad, the images are saved as HEIC. If, on the other hand, “Maximum compatibility” is selected, the camera saves the image as a JPEG. For videos, as already described, the file format is identical (.mov), but the codec used is different. H.265 is used for “High Efficiency” and H.264 for “Maximum Compatibility”. The file formats are retained when you import the images and videos from the iPhone and iPad into the Photos program on Mac. The images and videos retain their formats and codecs even when transmitted by airdrop or with the Digital Images program. This is irrespective of whether you have selected “Automatic” or “Keep originals” in the settings of the Photos app on the iPhone, as long as Mac is installed with Sierra or later. Because these versions of macOS can cope with the new formats. When transferring to a Windows PC, on the other hand, you should set “Automatic” to prevent the images and videos from being unable to open there. If in doubt, they will be converted.
It looks different if you send an image from the Photos app on your iPhone or iPad via email or message. It is automatically converted to a JPEG, since in this case the app cannot determine whether the recipient can do anything with the file format. And for videos, the program changes the coding from H.265 to H.264. The same applies to the Mac. Here, too, mail and messages convert the formats when sending pictures and videos. If, on
the other hand, you transfer photos or videos on the Mac HEIC using the H.265 codec to a web server, for example into the Dropbox, the format is retained. And if the recipient then can’t do anything with this format, there is a problem, as students in the USA had to learn who sent photos of examination-relevant documents via browser, but which then could not be opened. In this case you can open the images in the preview and export them as JPEG, PNG or TIFF. For the videos you take the QuickTime Player and deactivate the option “Use HVEC” when exporting.
A special feature are the live photos, in which a short video is recorded together with the picture and saved in a file. Live photos can be taken on the iPhone and iPad regardless of whether “High Efficiency” or “Maximum Compatibility” is selected in the camera settings. In the former case, the photo is saved as HEIC and the video is compressed with the H.265 codec; in the second setting, JPEG and H.264 are used. On the Mac, however, they can only be displayed in the Photos program if they have been imported there from the iPhone or iPad. If you later export them from photos, they become two files: an image and a video. Even if you import live photos from iPhone to Mac using the Digital Images program, you get these two files. However, something else happens when you transfer live photos via AirDrop. Here only the image file ends up as a JPEG on the Mac, the animation is lost. This does not make the files smaller. So the matter is not entirely transparent.
You can save a lot of space on the iPhone and iPad if you set “High Efficiency” in the specifications for the camera. As long as you are in the Apple universe, there are no problems with this setting for photos and videos. Especially since the objects are automatically converted into more compatible formats when they are sent by message or email. However, if you load the images and videos on a Mac with a browser on a web server or pass them on via data medium, you have to make sure that the recipient can also open or play the files if he does not have a Mac. (Macworld)