HEIC vs PNG

Why iPhones save photos as HEIC instead of PNG

HEIC (High Efficiency Image Container, 2017) is Apple's implementation of the HEIF standard using HEVC video compression for still images. It produces files 40-50% smaller than JPEG at equivalent quality and supports modern features that PNG cannot: HDR (High Dynamic Range), 10-bit and 12-bit color depth, image sequences (Live Photos), depth maps for portrait mode, and image stacks for burst captures.

Apple defaulted iPhone photos to HEIC starting with iOS 11 (2017) for one practical reason: storage. A 12 MP photo is roughly 3 MB as JPEG, 1.5 MB as HEIC, and 15-25 MB as PNG. For a phone with thousands of photos, the difference is gigabytes saved.

PNG (1996) sits at the opposite end of the spectrum: lossless compression, alpha transparency, universal compatibility from the late 90s onward, but file sizes 5-10× larger than HEIC for photographic content.

When you actually need to convert HEIC to PNG

1. Editing in software that doesn't read HEIC: older Photoshop versions (pre-2022), legacy Windows tools, GIMP without plugins, most server-side image processing pipelines.

2. Web upload requirements: many CMS platforms, e-commerce backends, and form submissions reject HEIC. Convert to PNG (or JPEG/WebP) before uploading.

3. Adding alpha transparency: HEIC supports alpha but most viewers ignore it. Converting to PNG preserves transparency for icon design, screenshots with transparent backgrounds, or compositing workflows.

4. Long-term archival: HEIC's universal support is improving but PNG has 30 years of guaranteed compatibility. For master copies you'll keep for decades, PNG (or its modern lossless cousin WebP-lossless) is safer.

5. Sharing with non-Apple users: Windows opens HEIC only via the (paid) HEIF Image Extensions. Android support is patchy. PNG works everywhere without configuration.

The hidden cost: file size explosion

Converting HEIC to PNG typically multiplies file size by 5-10×. A 2 MB iPhone HEIC photo becomes a 10-20 MB PNG. This isn't a flaw in PNG — it's a fundamental tradeoff. PNG stores every pixel exactly; HEIC throws away imperceptible detail in exchange for massive size savings.

For photographic content shared on the web, JPEG or WebP is almost always the better choice than PNG. Reserve PNG → HEIC conversion for cases where you genuinely need lossless preservation or alpha transparency.

When PNG → HEIC makes sense

The reverse conversion (PNG → HEIC) is rarer but valid when:

• You're archiving large quantities of photographic PNGs and want to reclaim disk space.
• You're preparing images specifically for Apple ecosystem display (iCloud Photos, Apple Photos library, AirDrop to iPhone).
• You need HDR or 10-bit color preservation that PNG can store but inefficiently.

For screenshots, icons, logos, or any image with sharp edges and few colors, PNG remains the better format and converting to HEIC saves little space while losing universal compatibility.

Conversion under the hood

KaijuConverter's HEIC ↔ PNG pipeline uses libheif (HEIC reading) and libpng (PNG writing) through ImageMagick. Conversion preserves:

• Color profiles: ICC profile embedded in HEIC carried over to PNG.
• EXIF metadata: camera info, GPS coordinates, timestamps preserved.
• Bit depth: 8-bit HEIC → 8-bit PNG; 10-bit HEIC → 16-bit PNG (closest standard).
• Alpha channel: if HEIC has transparency, PNG-RGBA preserves it.
• Live Photo motion: dropped (PNG cannot represent motion sequences).

For batch conversions of an iPhone Photos library, KaijuConverter processes multiple HEIC files in parallel and ZIPs the PNG outputs for single download.