Disclosure: This draft was generated with AI and checked against the cited primary sources, with a separate AI editorial review. It was prepared for the FrameSprite team, which has a commercial interest in FrameSprite. Proposed examples are not executed tests unless explicitly identified as recorded fixture results.
Do not treat zero alpha as redaction. Fully transparent pixels can still carry color data, and the file can contain metadata unrelated to the visible sprite. Inspect and sanitize the actual delivery artifact when private reference material must not travel with it.
Key Takeaways
- Visibility and retained file data are different properties.
- Separate privacy cleanup from edge-color preparation.
- Recheck the final package after every export or repack.
An invisible pixel is not necessarily empty
The PNG specification defines color samples and transparency separately. A transparent image can therefore retain RGB information that an ordinary composite preview does not show.
That hidden color can be intentional, for example when preparing edge colors for filtered rendering. It can also be unwanted source residue. The appropriate treatment depends on the delivery contract, not on whether a checkerboard preview looks clean.
Establish what may leave the project
List the inputs and metadata allowed in the public export. Private source photographs, confidential notes, and local directory details should not be assumed safe merely because the visible sprite hides them.
Inspect the exported pixels in a way that reveals color under transparency, and inspect metadata with an appropriate tool. If you maintain an inventory or transformation ledger in JSON, remember that RFC 8259 validates data representation, not whether its text is appropriate to publish.
Work on a delivery copy. Preserve the editable master and original inputs according to their handling requirements. Do not erase useful source information from the only recoverable production file to solve a packaging problem.
Example: a cropped reference behind the character
A composition contains a private reference layer that is hidden before export. The visible PNG looks correct. Depending on the export process, hidden source data may be absent, retained in metadata, or represented in otherwise invisible pixel values. The preview alone cannot establish which outcome occurred.
Inspect the actual exported file. If unwanted information remains, create a sanitized delivery using a documented process and verify that process's output. Renaming the file or flattening the visible preview is not proof that every hidden field was removed.
Preserve the rendering contract
A blanket instruction to make all transparent RGB black can damage filtered edge behavior. Review privacy requirements and rendering requirements together. Approved edge dilation may intentionally place nearby colors under zero alpha without containing private source material.
The CSS Color specification provides relevant context for color and alpha interpretation in browser rendering. The project's final engine or browser still needs its own visual check after sanitization.
Accept the package when the delivered file contains only permitted data and still renders as approved on required backgrounds. Record the inspection tool and exact output revision.
This is a proposed data-inspection procedure. No private residue, metadata removal, or rendering change was tested here. The guide does not claim that any particular exporter leaks hidden layers; its behavior must be checked directly.
Related workflow
For the adjacent decision, see straight vs premultiplied alpha sprites. Carry the animation handoff checklist with the release and retain the art reference board for visual decisions.
Prepared by the FrameSprite Workflow Team. Editorial method · Corrections. Primary documentation checked 2026-10-20.
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