HEIC to PNG

How to Convert to PNG

1. 1

   Drop your HEIC photos

   Up to 30 at a time. The limit is lower than the JPG converter's on purpose: a PNG of a 12-megapixel photo is 15 to 30 MB, and a bigger queue runs a browser tab out of memory.

2. 2

   Choose an optimisation level

   Level 2 is the default and a good balance. Level 6 finds a smaller lossless encoding of the exact same pixels but takes several times longer on a full-resolution photo.

3. 3

   Download the PNGs

   One photo comes back as a single .png, several as pulsarkit-heic-to-png.zip. Nothing about the image is lost along the way; only the file size changes.

When PNG is the right choice for a phone photo, and when it is not

PNG is lossless: the pixels that come out of the decoder are the pixels that end up in the file, byte for byte. That matters when the photo is an input to something else: cutting out a background, compositing layers, feeding a print workflow, or any process that would compound JPEG artefacts with every save. It matters much less when the photo is going straight to a website or a message, where a JPG at quality 90 looks the same and weighs a tenth as much. If you are about to email the result, convert to JPG instead; the switch is one step away in the pipeline below.

Orientation, transparency and bit depth

Rotation in a HEIC file can live in the container as an irot property or in the EXIF Orientation tag, and applying the wrong one leaves the photo sideways, which is the single most common defect in HEIC converters. Here both are read, whichever has not already been applied is baked into the pixels, and because PNG has no orientation tag of its own, that step is not optional. Transparency, if the container carries an alpha channel, is preserved; JPG cannot hold it at all. The bit depth switch writes a genuine 16-bit PNG for workflows that require one, though it is worth knowing that the HEIC decoder available in browsers hands over eight bits per channel, so a 16-bit file here is a faithful promotion of those values rather than extra precision recovered from the source.

What the optimisation level actually does

It does not change a single pixel. PNG compression works by predicting each pixel from its neighbours and then packing the differences, and there are many valid ways to make those choices. A higher level spends more processor time searching for the combination that packs smallest. Level 0 skips the search entirely and is fastest; level 2 is the sensible default; level 6 typically finds another few percent at several times the cost. Whichever you pick, decoding the result gives back exactly the same image. That equivalence is checked by a test that compares every pixel of a level 6 file against a level 2 one.

The decoder, and the licence it comes with

The HEIC half of this page is libheif 1.19.8, the reference open-source decoder, under the LGPL-3.0. That licence asks for two things: the component must stay separately replaceable rather than be fused into the rest of the code, and its source must be available. The WebAssembly module is therefore fetched as its own file from /libheif/ and never bundled, the licence text is at /libheif/LICENSE, and the unmodified sources of this exact version are at https://github.com/catdad-experiments/libheif-js/tree/v1.19.8 and https://github.com/strukturag/libheif. It is the same module HEIC to JPG uses, so if you arrive here from that tool it is already cached and there is nothing more to download.

Frequently asked questions

Guides

• Batch-Converting a Folder of iPhone HEIC Photos to JPGConverting a folder of iPhone photos to JPG sounds trivial, until a handful of them come back rotated the wrong way for no obvious reason.