PNG encoding is lossless; the full HEIC conversion is not
In Privacy mode, the browser pipeline decodes the primary HEIC image to 8-bit RGBA, then encodes those decoded pixels as PNG. PNG does not add JPEG-style lossy compression to those pixels, but it cannot recreate every original HEIC feature.
HEIC to PNG high quality means protecting the decoded pixels
PNG is useful when you want to avoid adding another JPEG-style lossy encoding step after HEIC decoding.
In Privacy mode, the browser encoder stores the decoded 8-bit RGBA pixel result with PNG's lossless compression. This protects that decoded pixel data, but the resulting PNG may be substantially larger than a JPG.
What the PNG output should not be assumed to preserve
The output is an image conversion, not a bit-for-bit copy of the HEIC container.
- 10-bit precision or HDR behavior from the original source
- ICC information, gain maps, or other color-related container data
- Depth data, auxiliary images, sequences, or non-primary frames
- Every original HEIC metadata field
EXIF is written back on a best-effort basis. Check the PNG result if metadata is important to your workflow.
HEIC to PNG quality FAQ
Answers about PNG compression, decoded pixels, metadata, and HEIC source features.
PNG encoding is lossless for the decoded pixels supplied to the encoder. In Privacy mode, the browser pipeline first decodes the HEIC primary image to 8-bit RGBA, so that does not mean the complete HEIC source is preserved losslessly.
Yes. PNG uses compression, but that compression is lossless for the decoded pixel data written to PNG. The resulting file can still be larger than a JPG.
No. Do not assume preservation of the complete HEIC container, 10-bit or HDR data, ICC information, gain maps, depth data, auxiliary images, sequences, or every original metadata field. EXIF is handled on a best-effort basis.