Image processing
What Metadata Is Removed When You Convert or Compress an Image?
Image conversion and compression usually work on decoded pixels, not the original container. When the browser writes a new JPEG, PNG, WebP, or AVIF, metadata is not automatically copied. This can improve privacy, but it can also remove rights, color, accessibility, and provenance information that mattered.
- Reviewed
- Reading time
- 8 minutes
Decode and re-encode creates a new container
A browser decoder turns the source into pixels. Canvas or a worker then writes those pixels with a selected format and quality. The encoder receives dimensions, pixels, and a few output settings; it does not automatically receive the source EXIF, XMP, IPTC, ICC, comments, or C2PA manifest.
Compression keeps the source format and dimensions in Photo Payload. Conversion keeps dimensions but changes format. Resizing changes dimensions as well. All three re-encode visible pixels and produce new metadata-light files.
Common information that is not carried forward
The exact source varies, but browser-created output generally omits these embedded payloads.
- Camera and exposure EXIF, including capture date, orientation, lens, and GPS.
- XMP editing history, ratings, labels, application fields, and sidecar relationships.
- IPTC captions, keywords, creator credits, copyright notices, and licensing fields.
- ICC color profiles, which can affect appearance in color-managed workflows.
- Content Credentials and other signed provenance that belongs to the original asset.
- Comments, thumbnails, and proprietary application blocks.
Operation comparison
Choose the narrowest operation that solves the task.
- Metadata cleanup
- Same format; existing pixel payload retained; metadata removed
- Compression
- Same format and dimensions; pixels re-encoded; metadata removed
- Conversion
- New format, same dimensions; pixels re-encoded; metadata removed
- Resize
- Selected dimensions and format; pixels resampled; metadata removed
Keep the original when rights data, exact color interpretation, provenance, or editing history may be needed later.
Removal is not always a benefit
Stripping GPS can protect privacy, but stripping creator and copyright fields can separate a work from its attribution. Removing an ICC profile may change how colors appear. Removing Content Credentials discards provenance rather than disproving it.
Archive the source, inspect the output, and use a metadata-aware professional workflow when fields must be preserved or rewritten across formats.
Sources and further reading
- MDN: HTMLCanvasElement.toBlob()
Browser API used to create encoded image blobs from canvas pixels.
- IPTC Embedded Metadata Manifesto
Industry principles for preserving descriptive and rights metadata with media files.
- C2PA Content Credentials specification
Explains asset-bound signed provenance and update chains.