HEIC

Definition and relationship to HEIF/HEVC

HEIC is a practical label rather than a standards body name: it refers to HEIF (High Efficiency Image File Format) files that contain images encoded with the HEVC (H.265) codec. HEIF itself is an ISO/IEC container format capable of holding still images, sequences, thumbnails, and rich metadata; HEVC is the compression technology applied to the image data inside that container. On Apple platforms, photos captured since iOS 11/macOS High Sierra typically use HEVC-compressed HEIF and are saved with the .heic extension, with MIME types such as image/heic and image/heic-sequence. While HEIF can carry other codecs, including AV1 (as AVIF), the industry generally uses “HEIC” to mean “HEIF + HEVC.” This distinction matters for compatibility and licensing, because browser support and patent terms are driven by the codec, not merely the container.

What “HEIC compression” means

“HEIC compression” is colloquial shorthand for HEVC intra-frame image compression used within a HEIF file. HEVC brings modern tools such as more flexible block partitioning, better intra prediction, transform coding, deblocking, and sample adaptive offset, yielding higher efficiency than JPEG’s DCT-based approach. In practice, HEIC photos are often 30–50% smaller than JPEG at visually similar quality, with support for 10‑bit depth, HDR signaling, and optional alpha planes. Quality and size vary by encoder settings, image content, and chroma subsampling, so gains are not uniform across all imagery. Unlike progressive JPEG, HEIC’s still images are not typically designed for incremental rendering over HTTP in browsers. The term can be confusing because HEIF is the container and HEVC is the codec; saying “HEIC compression” conflates the two but is commonly understood to mean HEVC-encoded still images stored in a HEIF container on Apple devices.

Summary: HEIC (HEVC-encoded images in the HEIF container) has broad device/OS-level support for capture and viewing, but minimal, non‑interoperable support in web browsers. It is not a deployable web image format; most sites transcode HEIC to JPEG, WebP, or AVIF for delivery.

HEIC is ubiquitous in mobile capture workflows, especially on iPhone, and can be previewed or edited across major desktop operating systems via native codecs or system frameworks. However, the web platform has not adopted HEIC for in-page rendering: common browsers don’t decode it in <img>, <picture>, CSS backgrounds, or canvas without plug-ins or native bridges. This gap makes HEIC a poor choice for direct web delivery. Production pipelines therefore treat HEIC as an input format: upload HEIC, then transcode and serve browser-compatible outputs such as AVIF or WebP, with JPEG as a universal fallback. This approach preserves the capture-side storage and quality advantages while avoiding compatibility hazards, broken images, and indexing issues on the public web.

Browser and crawler support

Chromium-based browsers (Chrome, Edge, Opera) and Firefox do not natively render HEIC/HEIF in HTML <img> or <picture>, nor as CSS images. Safari has OS-level support for viewing HEIC files, but WebKit’s web content pipeline does not provide reliable, universal HEIC rendering across devices and versions, so treating HEIC as a web-safe format is impractical. As a result, HEIC URLs risk broken images, placeholder icons, or file downloads instead of on-page display. Major search engines’ documentation for supported image types (for sitemaps and indexing) lists formats such as JPEG, PNG, WebP, GIF, and SVG; HEIC/HEIF is not included. Using HEIC-only URLs reduces eligibility for Google Images indexing, image-rich results, and social card previews, because crawlers and link unfurlers expect broadly supported web formats. Even where a crawler ingests a HEIC file, lack of rendering support can impair quality assessment and downstream uses like thumbnail generation and structured result enhancements.

Conversion and delivery options

Treat HEIC as an upload/input format and transcode for delivery. Robust pipelines decode with libraries such as libheif (used by ImageMagick and many SDKs) and produce a tiered set of outputs: AVIF for maximum compression efficiency where supported, WebP for broad modern coverage, and JPEG as a universal fallback. Delivery can be orchestrated via <picture> with type hints or through server-driven content negotiation using the Accept header, while avoiding image/heic since browsers rarely advertise support. Preserve orientation and transforms (HEIF’s irot/imir or embedded EXIF), ICC colour profiles, and XMP metadata as needed. Many iPhone photos embed Display P3 profiles; either retain the ICC or convert to sRGB to ensure consistent appearance on unmanaged displays. Handle special cases, such as Live Photos (paired HEIC + HEVC video) and HEIC sequences, by extracting a primary still for the web and storing the original as an archival asset. At scale, pre-generate common sizes, set long cache lifetimes with content-hashed URLs, and normalise transparency and bit depth during conversion to avoid unexpected output differences across formats.

Licensing and patent considerations

HEIF is an ISO container format, but HEIC’s defining characteristic—HEVC-compressed still images—brings patent licensing implications. HEVC is covered by multiple patent pools and licensors, and commercial encoding/decoding can require royalties depending on the use case and distribution. This is a key reason browser vendors have avoided shipping HEIC decoding for the open web. While end users on Apple devices can capture and view HEIC thanks to OS-level licences, deploying HEIC as a website delivery format may expose services to licensing obligations and compatibility issues. In contrast, AVIF (HEIF with AV1 still-picture coding) and WebP are offered as royalty-free for most uses, which aligns better with browser policies and broad web deployment. Organisations that process HEIC uploads server-side should review codec library licences and any patent pool requirements for their jurisdiction and scale, and prefer transcoding outputs to royalty-free web formats for distribution to end users.

Implementation notes

Identify HEIC by container brands and MIME types rather than only by file extension. HEIF files include an ftyp box with brands such as heic, mif1 (still images), or msf1/hets for sequences; common MIME types are image/heic, image/heif, image/heic-sequence, and image/heif-sequence. When decoding, respect HEIF’s transform boxes (irot/imir) and any EXIF orientation to avoid rotated or mirrored outputs. Normalise colour by preserving embedded ICC profiles or converting to sRGB, especially when producing JPEG or WebP for browsers with varying colour management defaults. For delivery, prefer a conservative <picture> stack (AVIF, then WebP, then JPEG) and never advertise HEIC in srcset/type attributes. Do not rely on Accept for HEIC; mainstream browsers do not send image/heic. In storage, keep the original HEIC as the source of truth, generate deterministic derivatives (content-hashed filenames), and attach metadata about bit depth, colour space, and transparency. Validate HEIC uploads defensively, as Live Photos and burst sequences can contain multiple items; choose the primary item for still-image workflows. Monitor error logs for decode failures due to uncommon profiles, and pin library versions to avoid surprises from codec changes.

Comparisons

Compared with JPEG, HEIC typically offers much better compression at similar quality and supports higher bit depths and modern colour, but lacks web compatibility. Versus WebP, HEIC’s efficiency on photographic content is competitive, yet WebP is widely supported in browsers, making it a safer delivery choice. Against AVIF, HEIC is generally faster to encode and decode on mobile hardware that accelerates HEVC, but AVIF often achieves equal or smaller file sizes and is royalty-free with growing browser support. For transparency and limited animation, HEIC can store alpha and sequences, but real-world web use favours WebP and AVIF for these features. From a web performance and SEO standpoint, HEIC is best treated as an ingestion/source format, with AVIF/WebP/JPEG providing the interoperable outputs for page rendering, indexing, and social sharing.

FAQs

Can I use HEIC images directly on my website?

It is not advisable. Most browsers cannot render HEIC in <img> or CSS, and some crawlers do not recognise HEIC/HEIF as a supported format. Direct links may trigger downloads or broken placeholders, harming UX and SEO. Convert HEIC uploads to AVIF or WebP with a JPEG fallback, and serve using <picture> or server-side content negotiation so users and bots receive formats they can display and index.

Will Google index pages whose primary images are HEIC?

Google’s documented supported image formats for sitemaps and image indexing do not include HEIC/HEIF. While pages themselves can be indexed, relying on HEIC-only assets reduces eligibility for image search features, rich results that depend on images, and high-quality thumbnails. Providing crawlable AVIF/WebP/JPEG versions with proper markup maximises indexing reliability and presentation in search surfaces.

Does HEIC support transparency and animation like WebP or AVIF?

HEIF supports alpha planes and image sequences, and HEIC inherits those capabilities for HEVC-encoded items. In practice, typical smartphone photos are opaque single frames, and web browsers don’t render HEIC sequences. If you require transparency or lightweight animation on the web, AVIF and WebP are the practical choices because they are supported by modern browsers and tooling for in-page rendering.

Why do iPhones use HEIC if it’s not web-friendly?

HEIC reduces on-device storage and upload sizes while enabling higher bit depth and modern colour, and Apple licenses HEVC at the OS level for seamless capture and viewing. The web ecosystem prioritises open, royalty-free formats and broad interoperability, which has kept HEIC out of browsers. The common workflow is to capture in HEIC for efficiency, then transcode to web-safe formats for publishing and sharing beyond Apple platforms.

What should I watch for when converting HEIC to AVIF or WebP?

Pay attention to orientation (apply HEIF transforms), colour profiles (retain ICC or convert to sRGB), bit depth (8‑bit vs 10‑bit), and chroma subsampling. For photographic content, AVIF at moderate quality can be substantially smaller than JPEG and often smaller than WebP, but encoding is slower; budget CPU time or use queued processing. Validate transparency if present, and ensure metadata policies meet privacy and SEO needs (e.g., stripping EXIF GPS while keeping alt text and filenames descriptive).