The tip circulates every year or so in forum threads and short videos: you do not need a converter, just rename the file from photo.heic to photo.jpg and everything opens it. The instruction is easy, the result looks convincing in whichever app the tip's author used, and it is quietly wrong in a way that costs people real time.
What the rename actually changes
An extension is a label, not a container. The bytes do not notice: the file still starts with the HEIC signature box and still holds an image compressed with HEVC, the codec family Windows ships no decoder for. Renaming a HEIC to .jpg changes what the operating system assumes before it opens the file, and nothing about what it finds after.
Where the trick appears to work
Permissive readers — VLC, some image viewers, a few drivers — ignore extensions and sniff the actual content, then decode HEVC because they can. If that was the app in the video, the rename looks like a complete fix. The catch is that every program guesses differently. The same file opens in one app and shows a broken icon in the next, because the second app trusted the label and handed HEVC bytes to a JPEG decoder. A format choice that depends on which program is looking at it is not a fix; it is a file that fails somewhere else.
Where it fails in practice
- Upload forms that validate by extension accept the file, then the platform's image pipeline fails to build a preview or rejects it later — after you have closed the tab thinking it worked.
- Thumbnailers and camera-import utilities that key on codec classification index the file wrongly or skip it entirely.
- Archives and backup tools that check content flag the mismatch as corruption.
- Email and chat previews show a blank frame, because the resizing service behind them does not decode HEVC.
What actually fixes it
A real conversion re-encodes the pixels: decode HEVC, write JPEG. That is the only step that changes what is inside the file, and in the HEIC converter it takes a couple of seconds per photo, in the browser, without uploading anything. The rename gets remembered as a shortcut precisely because it is one instruction — the conversion is one instruction too, and it is the one that holds up in every program that opens the result.