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Plain-language definitions for every term that shows up when you work with HEIC, HEVC, and PNG photos.
High Efficiency Image Coding — Apple's default image format on iPhones since iOS 11 (2017). Stores photos in about half the space of JPG at the same quality by using the HEVC video codec to compress still images. Internally a container built on HEIF.
High Efficiency Image File Format — the ISO/IEC 23008-12 standard container that HEIC is based on. HEIF can carry HEVC-encoded images, image sequences (like Live Photos), depth maps, and alpha channels in a single file.
High Efficiency Video Coding (also called H.265) — the video compression standard Apple repurposed to compress HEIC still images. Roughly 50% more efficient than JPEG's older compression at equivalent quality.
Advanced Video Coding — the predecessor to HEVC, still used by most MP4 videos. Less efficient than HEVC but with broader device support; relevant because some older phones store videos as H.264 even when photos are HEIC.
Short for coder/decoder. The algorithm that compresses (encodes) and decompresses (decodes) image or video data. HEIC uses the HEVC codec; JPG uses DCT-based JPEG compression.
The file wrapper that holds encoded image data plus metadata. A .heic file is a HEIF container carrying HEVC-encoded images inside. Containers describe how bytes are organized, codecs describe how pixels are compressed.
A compression method that preserves every pixel exactly — decompressing the file gives you bit-for-bit identical data. PNG is lossless, which is why it's ideal for editing, logos, and screenshots where quality matters.
A compression method that discards some image data to reduce file size, trading quality for space. JPG and HEIC are lossy. The quality loss is often invisible at normal viewing distances.
Portable Network Graphics — a lossless image format with alpha channel support, standardized in 1996. Universal browser and OS support, ideal output format when converting from HEIC because no quality is lost in the decode step.
Joint Photographic Experts Group — the dominant lossy image format for photos since the 1990s. Smaller files than PNG but without transparency. A common alternative output target when HEIC file size matters more than quality.
The transparency channel in an image, separate from red/green/blue. PNG and HEIC both support alpha; JPG does not. Critical for logos, overlays, and composited graphics where you need a transparent background.
Exchangeable Image File Format — metadata embedded in photo files describing camera model, exposure, date, GPS coordinates, orientation, and more. Most converters preserve EXIF when converting HEIC to PNG; ours offers it as an option.
A grayscale layer that records distance from the camera for each pixel, captured on iPhones with dual/multi-lens cameras. Used for Portrait mode blur. Lost when flattening HEIC to PNG because PNG has no standard depth-map channel.
iPhone feature that captures a 1.5-second video before and after the still shot. Stored as a HEIC still plus an HEVC-encoded MOV. Converting to PNG keeps only the still image; the video portion is not preserved in PNG.
Processing that runs in your browser rather than on a remote server. Our HEIC-to-PNG converter decodes HEVC and writes PNG entirely on your device — photos never leave the browser, which is why it's private and works offline once loaded.
Dots per inch / pixels per inch — units describing how densely pixels are packed when the image is printed or displayed. An image's pixel dimensions matter for web; DPI only becomes meaningful when printing. HEIC-to-PNG conversion keeps pixel dimensions and DPI metadata intact.
The number of bits used per color channel per pixel. 8-bit per channel (24-bit total RGB) is standard; 10-bit HEIC stores richer highlights and shadows. PNG supports 8-bit and 16-bit per channel but not 10-bit, so very rare HEIC photos in 10-bit HDR drop to 8-bit on conversion.
A compression shortcut that stores color (chroma) at lower resolution than brightness (luma). JPG commonly uses 4:2:0; HEIC often uses 4:2:0 too but handles it better. PNG does not subsample — every pixel keeps full color. This is one reason PNG files look slightly sharper on text and edges.
Metadata describing the color space of an image (sRGB, Display P3, Adobe RGB, etc.). iPhone photos are usually tagged Display P3 for wider colors. Preserving the ICC profile when converting HEIC to PNG ensures colors stay accurate across browsers and editors.
A sequence of rapid photos captured by holding the shutter. Stored by iPhone inside a single HEIC container as an image sequence. Converting a burst to PNG produces individual PNG frames — one per photo in the sequence.
