HEIC explained: why your iPhone photos won't open

You come back from a trip with four hundred photos, plug the phone into a laptop, drag the folder across, and then nothing opens. The files end in .HEIC and the computer either shows a grey placeholder or refuses outright. It is one of the most common complaints people have about the iPhone, and the explanation is more interesting than "Apple invented another format nobody else uses."

What HEIC actually is

HEIC stands for High Efficiency Image Container, and the word container is doing real work there. It is a wrapper defined by the HEIF standard, and it can hold one image, or forty, plus a stack of extra data alongside them. The picture inside is normally compressed with HEVC — also known as H.265 — which is a video codec. The same codec family that carries 4K streams on Netflix and Blu-ray discs.

Apple's move was to take a single intra-frame from that video codec and store it as a still photo. That sounds odd until you compare the two compression schemes. JPEG's algorithm was finalised in 1992. HEVC intra-frame coding has 35 directional prediction modes for guessing what a block of pixels looks like from its neighbours, block sizes that adapt from 4×4 up to 64×64 depending on how busy the region is, and a deblocking filter that tidies the seams afterwards. JPEG has an 8×8 grid and a quantisation table. Thirty years of research sits between them, and it shows in the file size.

Why Apple switched in iOS 11

Storage, mostly. A 12-megapixel photo that lands at 3–4 MB as a high-quality JPG comes in near 1.5–2 MB as HEIC, and if you put them side by side on a screen you will not see the difference. Multiply that by the ten thousand photos sitting on a 64 GB phone and it is the difference between having room for the holiday and not.

The container brought other things Apple had been bolting onto the side of JPG for years:

• Depth maps. Portrait mode stores a per-pixel distance map next to the image. That is how you can change the background blur days after the shot was taken.
• Live Photos. The still frame and the second and a half of motion either side live in one file, rather than a .JPG and a .MOV that have to be kept together or the effect breaks.
• Burst sequences. Forty frames in one container instead of forty files cluttering the roll.
• 16-bit colour. JPG tops out at 8 bits per channel — 256 levels. HEIC handles 10-bit and beyond, which is why HDR sunsets in HEIC do not show the banded stripes you get in a JPG sky.
• Non-destructive edits. Crops and filters stored as instructions, with the untouched original still in the file.

So why won't it open anywhere?

Patents. HEVC is covered by a thicket of them, and unlike earlier codecs the holders never agreed on one licensing pool. Three separate groups ended up collecting royalties on overlapping claims. Anyone shipping an HEVC decoder has to pay someone. That works fine for Apple, which builds decoding into its own silicon and folds the cost into the price of the phone. It works badly for everyone giving software away for free.

What that produces in practice:

• Windows can decode HEIC, but the codec is a separate item in the Microsoft Store called HEVC Video Extensions, and it costs money. Some PC makers pre-license a free variant, which is why one Windows laptop opens your photos and the one next to it does not.
• Android gained HEIF decoding in version 10, but manufacturer gallery apps handle it unevenly and anything older simply cannot.
• Browsers mostly refuse. Safari renders HEIC. Chrome, Firefox and Edge will not display it inline, so an HEIC dropped into a web page shows as a broken image icon.
• Older software — Photoshop before CC 2018, most GIMP builds, anything from the Windows 7 era, and a long tail of print kiosks and government upload forms — has never heard of the format.

What this looks like from your side

The symptoms are always the same three or four. A double-click gives you "this file format is not supported." A job application form rejects the upload and says JPG or PNG only. The photo you attached to an email arrives as a grey box for the recipient. Or the photo kiosk at the shop scans the USB stick and reports the folder as empty, which is a particularly annoying way to find out.

Why the problem seems random

Here is the part that confuses people most. Sometimes the photos copy across as ordinary JPGs and everything is fine, and the next time the same phone and the same cable produce HEICs. That is a single setting: Settings > Photos > Transfer to Mac or PC, with two options. Automatic quietly converts everything to JPG on the way out of the phone. Keep Originals hands over the raw HEIC untouched.

Only that transfer path honours the setting, though. AirDrop to a Mac keeps HEIC. Some third-party file managers pull the originals off the camera roll and bypass the conversion entirely. Uploading through an app depends on what the app asks for. So the same phone genuinely does behave differently depending on how the photo leaves it, and the setting most people never look at is the one deciding.

Stopping it at the source

If you would rather not deal with any of this, go to Settings > Camera > Formats and choose Most Compatible. From that point the camera writes JPG for stills and H.264 for video, and everything you shoot opens anywhere.

The trade-off is real, so decide it deliberately. Your photos will take roughly twice the space for the same visual quality. You lose 10-bit colour on HDR stills. Live Photos still work, but as the old JPG-plus-MOV pair. And the setting is not retroactive — it changes nothing about the thousands of HEIC files already on the phone. A few high frame rate video modes also stay on HEVC regardless, because H.264 cannot handle them.

Converting the ones you already have

For files that already exist, converting is the fix. AllConvert does this in the browser, so the photos never leave your machine — worth knowing when the batch is family pictures rather than screenshots.

• HEIC to JPG is the default answer. Universal support, sensible file size, and the right choice for upload forms, printing, email attachments and anything older than about 2018.
• HEIC to PNG re-encodes without adding a second layer of lossy compression, so pick it when the image is heading into further editing, or when it is a document scan or diagram where sharp edges matter more than size. Expect large files.
• HEIC to WEBP is for the web. WEBP is roughly 25–30% smaller than JPG at matched quality and every current browser renders it, so it is the sensible target if the photos are going onto a site.

If the converted files still come out bigger than you want, run them through the image compressor afterwards to trade a little quality for size. For a wider comparison of what each format is good at, the image formats guide covers the rest.

What you lose in the conversion

Converting HEIC to JPG flattens the container down to one plain image, and everything the container was carrying goes with it. The depth map disappears, so no more adjusting the portrait blur later. A Live Photo becomes the still frame and nothing else — the motion is gone. A burst becomes a single picture. 16-bit colour is squeezed into 8, which is only visible in gradients like skies and studio backdrops, but visible it is.

The file also gets bigger. That sounds backwards until you remember what HEIC was doing: matching JPG's quality in half the bytes. Undo that and you land back at JPG's size for the same picture, give or take. A 1.8 MB HEIC typically comes out around 3.5 MB as a high-quality JPG.

Because of all that, the sane habit is to convert copies and leave the originals alone. Keep the HEICs in iCloud or on a backup drive, send JPGs to whoever needs them, and you get compatibility today without throwing away data you cannot get back.