Why Apple HEIC photos fail on Windows and how to convert them

Modern iPhones save photos as HEIF/HEIC (High Efficiency Image Container) by default (Apple explains this in its note on HEIF and HEVC media on Apple devices). HEIC files are about half the size of JPEGs and keep 10-bit and 12-bit colour depth. But they often fail to open when you move them to a Windows PC, submit them to a job portal or upload them to a web app. The fix is a one-step HEIC to JPG conversion.

Understanding the HEIC / HEIF Specification

HEIC stores the image data using High Efficiency Video Coding (HEVC/H.265) compression. This gives it some clear advantages over JPEG, which is 30 years old:

• Superior Color Gradation: Supports 10-bit and 12-bit high dynamic range (HDR) colour, which prevents visible bands in skies and shadows.
• Alpha Channel & Burst Stacks: One HEIC file can hold several burst shots, depth maps and Live Photo video clips.
• 50% Smaller File Size: Looks as good as a JPEG that is more than twice its size.

Why Windows and Web Forms Reject HEIC

Windows does not include HEVC codec licences by default, because of patent royalty fees. As a result, Windows Photo Viewer, File Explorer thumbnails and older image programs show "Format not supported" errors.

How to Convert HEIC to Universal JPG / PNG Fast

1. Client-Side WebAssembly Decoding: Using libheif compiled to WebAssembly, your browser decodes the HEVC image data itself.
2. Preserve EXIF Metadata: A good conversion copies the camera aperture, shutter speed, timestamp and orientation tags into the JPEG.
3. Set Quality Between 85% and 92%: For photos, a JPEG quality of about 88% keeps almost all the detail while keeping the file small. If you need transparency or a lossless copy instead, convert to PNG.