HEIC MIME Type

What does image/heic mean?

The image/heic media type identifies a High Efficiency Image File that contains one or more images encoded with HEVC, also called H.265. HEIC uses the broader High Efficiency Image File Format container, or HEIF, which is based on the ISO Base Media File Format.¹

The distinction matters. HEIF is a container architecture that can carry images encoded with different codecs. HEIC is the HEVC-specific form. IANA permits image/heic only when the file declares a compatible heic, heix, heim, or heis brand and contains HEVC-coded image items.¹

HEIC can hold more than a flattened photograph. A file may include multiple images, thumbnails, alpha or depth auxiliary images, tiles, edits expressed as derived images, and EXIF or XMP metadata. Software that only exports the primary image can silently leave some of that information behind.²

How can you identify a HEIC file?

The usual extension is .heic. IANA also assigns .hif to both image/heic and image/heif; .heif belongs to image/heif.¹ In practice, .heic is the clearest suffix for an HEVC-coded still image.

IANA records no fixed magic number for HEIC.¹ A typical file has an ISO Base Media File Format ftyp box near the beginning, but ftyp alone is not a HEIC signature. MP4, AVIF, and other related formats use the same box structure. A detector needs to parse the File Type Box and look for a compatible HEIC brand such as heic or heix.

Renaming a JPEG or generic .heif file to .heic does not change its codec or brands. If a file fails to open, inspect its container with a format-aware utility such as heif-info, ffprobe, or MP4Box instead of trusting the filename.

Where did HEIC come from?

The first HEIF specification became an ISO standard in June 2015 as part of MPEG-H. Its published specification is ISO/IEC 23008-12.²¹ HEIF separated the container from the codec, bringing an approach long used for video to still images. Encoded images are stored as items, while timed image sequences can be stored in tracks.

Apple made HEIF and HEVC a mainstream photo workflow with iOS 11 and macOS High Sierra in 2017. Supported iPhones and iPads can capture photos in the high-efficiency format, and Apple devices can convert them to more compatible formats when sharing.³ IANA registered image/heic and the related image/heif media type on July 30, 2018.¹

How to open an image/heic file

Apple Photos and Preview open HEIC images on current Apple platforms. Apple documents support beginning with iOS 11 and macOS High Sierra 10.13, subject to device limitations for some media.³

Web support is much narrower than operating-system support. Safari 17 added HEIC image support, while Apple still recommends treating it as an alternative because other platforms and browsers may not support it.⁴ For a public website, provide a broadly supported fallback:

<picture>
  <source srcset="photo.heic" type="image/heic">
  <source srcset="photo.avif" type="image/avif">
  <img src="photo.jpg" alt="A descriptive alternative">
</picture>

Send the exact Content-Type: image/heic header. Do not label arbitrary HEIF or AVIF content as HEIC merely because the browser can decode one of those formats.

HEIC support in Poly

Poly maps image/heic and .heic filenames to its HEIC image type. It separately maps image/heif and .heif to its general HEIF type. The filename-only inference path does not currently map IANA's .hif extension, so a .hif upload needs an accurate media type to enter the HEIC pipeline.

For either HEIC or HEIF, Poly's image loader decodes the primary image with libheif and applies container transformations. The indexing pipeline then creates its normal WebP thumbnail set, extracts pixel dimensions and readable EXIF fields, and generates a visual embedding for similarity and color search. HEIF rotation stored in an irot box is handled without applying an EXIF orientation a second time.

The image viewer transcodes HEIC to a browser-friendly PNG when needed and can fall back to a generated thumbnail. It does not depend on the browser decoding the original HEIC. The tradeoff is that the viewer represents the primary rendered image rather than exposing every image, depth map, alpha item, or container relationship.

The Poly agent can inspect that rendered image. Plain images are not OCR'd, so words visible in a HEIC photo do not become full-text search terms. The agent also does not receive the original container structure or all embedded metadata merely because it can see the rendered image.

HEIC compared with JPEG and AVIF

These formats solve overlapping problems, but they differ in compatibility and container capabilities.

HEIC can use fewer bytes than JPEG at a similar perceived quality, but there is no universal savings percentage. The result depends on the source, encoder, chroma sampling, bit depth, and quality target. Apple describes HEIF and HEVC as more storage-efficient than JPEG and H.264 at the same visual quality, but production decisions should come from tests on representative images.³

HEIC and AVIF share the HEIF-family container model, not the same coded image data. Supporting one does not guarantee support for the other. AVIF generally has much broader browser support, while HEIC fits especially well into Apple capture and native-app workflows.⁴

Converting HEIC safely

Choose the destination according to what must survive:

• Convert to JPEG for maximum viewing compatibility when transparency, HDR, and auxiliary images are unnecessary.
• Convert to PNG for a widely editable lossless rendering or when you need an alpha channel.
• Convert to AVIF for modern web delivery, after checking browser requirements and color handling.
• Keep the original HEIC when it contains HDR, depth, edits, burst images, or metadata that a single rendered export could discard.

Apple Photos and Preview can export a HEIF image as JPEG or PNG. Preview can also export supported images as HEIC.³⁵

Check color management as well as pixels. An SDR conversion can flatten HDR highlights, and stripping an ICC profile or color information can change appearance. When sharing from an Apple device, automatic compatibility conversion may create a JPEG instead of sending the original HEIC.³

Is HEIC the same as HEIF?

Not exactly. HEIF names the general container format. HEIC is a HEIF file constrained to HEVC-coded image items and specific compatible brands. People and applications often use the names interchangeably because Apple's common HEIF photos are HEIC files, but the media types express different promises.

Use image/heic for a conforming HEVC-coded HEIC file. Use image/heif for a general mif1 HEIF image whose codec-specific subtype is not more appropriate. Use image/avif for a conforming AV1 Image File Format file.