Xiaomi
Convert HEIF Photos to JPEG Before Sending auf Xiaomi
Xiaomi phones can capture photos in HEIF format to save storage space. HEIF files are smaller than JPEG but not every app, messenger, or older device can open them.
When that happens, a photo you send looks fine in your own Gallery but arrives as a grey box, a generic file icon, or an unreadable attachment on the other end. This is not a bug in the Gallery app. It simply means the receiving device or app has no HEIF decoder.
MIUI solves this with a built-in conversion toggle. When enabled, the Gallery app converts a HEIF photo to JPEG right before it leaves your phone, so the file that gets sent is already in a format almost every device and app can display.
To check or change this behavior, go to Tap on Gallery ➔ Open the Menu ➔ Tap on Settings ➔ Enable or disable Convert HEIF to JPEG before sending.
Turn the option on if you regularly send photos to people using non-Xiaomi phones, older Android devices, or apps that reject HEIF attachments. Turn it off only if you specifically need the original HEIF file, for example when sending to another HEIF-compatible device to keep the smaller file size.
Keep in mind that JPEG files are usually larger than the original HEIF version, so converted photos take slightly more time and data to upload.