Overview
HEIC (High Efficiency Image Container) is a modern image format based on the HEIF (High Efficiency Image File Format) standard that uses HEVC (H.265) video codec technology to compress still images. Apple adopted HEIC as the default photo format for iPhones and iPads starting with iOS 11 in 2017, making it one of the most widely captured image formats in the world even though many users are unaware they are shooting in it.
The format delivers approximately 50% file size savings compared to JPEG at equivalent visual quality. This remarkable compression efficiency is achieved by leveraging the advanced prediction, transform, and entropy-coding tools of the HEVC codec — the same technology that compresses 4K and 8K video. A single HEIC file can store a photo at full resolution with dramatically less storage consumption, which is why Apple chose it to help users conserve space on their devices.
Beyond compression, HEIC supports features that JPEG cannot: 10-bit and 12-bit color depth for HDR photography, alpha-channel transparency, image sequences (Live Photos on iPhone store a burst sequence plus a key frame in a single HEIC file), depth maps for portrait-mode bokeh effects, and auxiliary images such as thumbnails and gain maps. The container can also hold multiple independent images, making it a versatile packaging format for computational photography workflows.
History
The HEIF container format was standardized by the Moving Picture Experts Group (MPEG) as ISO/IEC 23008-12 in 2015, building on the ISO Base Media File Format (ISOBMFF, ISO 14496-12) used by MP4 video files. HEIF itself is codec-agnostic — it can wrap images compressed with HEVC, AV1 (producing AVIF files), or other codecs. When HEVC is the compression codec, the resulting files are typically given the .heic extension.
Apple's adoption of HEIC in iOS 11 (September 2017) was the catalyst for mainstream awareness. By making it the default capture format for hundreds of millions of iPhones, Apple instantly created a massive library of HEIC images worldwide. Microsoft added HEIF/HEIC support to Windows 10 via a store extension, Google added Android support in Android 10, and Samsung phones began shooting HEIC optionally. However, web browser support remains limited — as of 2024, Safari supports HEIC natively, but Chrome and Firefox do not, largely due to HEVC patent licensing complexities.
Technical Details
HEIC files use the ISO Base Media File Format structure, consisting of typed boxes (atoms) that contain metadata, image items, and their properties. The primary image item is HEVC-encoded using intra-frame prediction (I-frame only, no inter-frame dependencies). HEVC divides the image into Coding Tree Units (CTUs) of up to 64x64 pixels, applies angular intra prediction from 35 directional modes, transforms residuals using integer DCT and DST, quantizes coefficients, and entropy-codes them with Context-Adaptive Binary Arithmetic Coding (CABAC).
The ISOBMFF container supports storing multiple image items with relationships between them: a primary image, a thumbnail, an alpha plane, a depth map, and an HDR gain map can all coexist in a single file. Image properties like rotation, cropping, color profile (ICC or CICP), and EXIF metadata are stored as item properties associated with specific image items. Live Photos are implemented as an image sequence item containing multiple HEVC-compressed frames with timing metadata, paired with an embedded audio track.
Pros & Cons
Pros
- Approximately 50% smaller file size than JPEG at equivalent visual quality
- Supports 10-bit and 12-bit color depth for HDR and wide color gamut imagery
- Can store multiple images, depth maps, alpha planes, and sequences in one file
- Native support on all Apple devices (iOS, macOS) and most Android devices
- Preserves Live Photos, portrait depth data, and computational photography metadata
Cons
- Limited web browser support due to HEVC patent licensing issues
- Many image editors and web services do not accept HEIC directly
- Patent royalties on HEVC codec create legal complexity for implementers
- Conversion to JPEG is often needed for sharing on non-Apple platforms
- Encoding is computationally intensive compared to JPEG
Common Use Cases
- Default photo capture format on iPhones and iPads for storage-efficient shooting
- Storing HDR photographs with 10-bit color depth and wide color gamut
- Packaging Live Photos with image sequences and audio in a single file
- Preserving portrait-mode depth maps for post-capture bokeh adjustment
- Reducing cloud storage consumption for large photo libraries on iCloud
- Archiving high-quality photos at half the storage cost of equivalent JPEGs