HEIC to JPG

Understanding HEIC: Why Your iPhone Doesn't Just Use JPG

HEIC (High Efficiency Image Container) is a file format that wraps images compressed with HEVC — the same H.265 codec used for 4K video streaming. Apple adopted HEIC as the default photo format in iOS 11 (2017) because it produces files roughly 50% smaller than equivalent-quality JPGs. A 12-megapixel iPhone photo that would be 3-4 MB as a JPG typically lands around 1.5-2 MB as HEIC, with no visible quality difference.

Beyond smaller files, HEIC supports capabilities that JPG cannot match. It stores 10-bit color depth in the Display P3 wide color gamut — over a billion colors compared to JPG's 16.7 million in 8-bit sRGB. It supports alpha channels (transparency), depth maps from Portrait mode, image sequences (burst shots), and even embedded video clips (Live Photos). A single HEIC container can hold multiple items that would require several separate files in other formats.

The tradeoff is compatibility. Windows versions before 11 don't include an HEVC decoder by default. Most Android devices can't open HEIC files. Web platforms, social media uploaders, email clients, and many desktop applications still expect JPG or PNG. This isn't a quality problem — it's a compatibility problem, and it's the reason HEIC-to-JPG conversion remains one of the most common image operations for iPhone users.

What Happens During HEIC to JPG Conversion

The conversion pipeline has several stages. First, ImageMagick decodes the HEVC-compressed image data from the HEIC container, reconstructing the raw pixel grid. HEIC files from iPhones typically use the Display P3 color space — a wide gamut that covers roughly 25% more colors than the sRGB space used by JPG. ImageMagick maps Display P3 values into sRGB during decoding, which means colors that fall outside the sRGB gamut get clipped. In practice, this is subtle — you'll only notice it in photos with extremely vivid sunsets, neon signs, or saturated greens.

Bit depth also changes. HEIC stores 10 bits per channel (1,024 tones per color), while JPG is limited to 8 bits per channel (256 tones). This reduction from over a billion possible colors to 16.7 million is imperceptible for most photographic content but can introduce very slight banding in smooth gradients — the kind you'd see in a clear sky fading from deep blue to white.

The decoded RGB data is then passed to the JPEG encoder, which applies lossy DCT (Discrete Cosine Transform) compression. The encoder splits the image into 8×8 pixel blocks, transforms each block into frequency coefficients, and quantizes those coefficients at the specified quality level (1-100, default 75). Lower values discard more data, producing smaller files with more visible artifacts.

The strip option (enabled by default) removes EXIF metadata, GPS coordinates, ICC color profiles, and other embedded data during conversion. This reduces file size and removes potentially sensitive location information. You can disable stripping in Configuration Options if you need to preserve metadata in the output JPG.

Live Photos, Burst Shots, and Depth Maps: What Gets Preserved

HEIC is more than a single-image format — it's a container that can hold multiple data types simultaneously. An iPhone HEIC file may contain a still image, a 3-second video clip (Live Photo), burst sequences, a depth map from Portrait mode, and an HDR gain map for adaptive display. When you convert to JPG, only the primary still image is extracted. Everything else is discarded because JPG is a flat, single-image format with no container capabilities.

Live Photos: The short video clip that captures motion before and after the shutter press is stored alongside the still frame in the HEIC container. Converting to JPG gives you the still frame only — the video is lost. If you need the video portion, export it as a MOV file from the Photos app on your iPhone before converting.

Burst mode: When you shoot a burst on iPhone, each frame is typically a separate HEIC file. Converting any individual burst frame works normally. If the burst is stored as a sequence within a single HEIC container, only the primary (selected "best") frame is extracted during conversion.

Depth maps: Portrait mode photos embed a depth map that encodes the distance of each pixel from the camera. This data powers the background blur (bokeh) effect and allows after-the-fact focus adjustments in the Photos app. The JPG output is a flat 2D image — the depth information is stripped, and the blur effect is baked into whatever state it was in when the still image was captured.

Quality Settings and File Size: What to Expect

Because HEIC already uses aggressive HEVC compression, the file size difference between HEIC and JPG is smaller than you'd see with lossless formats like PNG. HEIC has already discarded imperceptible data — converting to JPG re-encodes what remains using a different lossy algorithm. The table below shows typical sizes for common iPhone photo types:

Notice that at quality 85-90, the JPG file can actually be larger than the original HEIC. This is because HEVC is a more efficient codec than JPEG's DCT — it takes more bytes for JPG to represent the same visual quality. Quality 75 is still a good default for sharing and web use. For archival or print purposes, quality 85-90 preserves more detail at the cost of larger files. Learn more about how images lose quality after conversion.

The three fit modes control what happens when you set a target width or height. Max (default) fits the image within the specified bounds without upscaling. Crop fills the dimensions exactly and trims overflow. Scale forces the exact dimensions, which may stretch the image if the aspect ratio doesn't match. If you don't set any dimensions, the original pixel size is kept.

For further size reduction after conversion, you can run the JPG through the image compressor. Learn more about the JPG format and its compression characteristics, or compare HEIC vs JPG in detail.