Browser-local image evidence
PNG Transparency Checker
Read the file structure, count every decoded alpha value, catch a painted checkerboard, and inspect the edge on four backgrounds—without uploading the image.
Step 1
Choose the final PNG
Use the downloaded or exported asset—not a screenshot of its preview.
The tool rejects a renamed JPEG even if its filename ends in .png. It is a focused delivery check, not a full PNG conformance certification.
Waiting for a PNG.
Try a known fixture
These original files have different ground-truth outcomes.
Step 2
Inspect the evidence
File and pixel facts
Step 3
Review the edge on four backgrounds
Human release gate
Zoom into curves, hair, shadows, and thin lines.
Confirm the subject is complete, no background islands remain, and the approved file hash still matches the delivered bytes. Review every frame separately if the APNG marker is present.
Learn the method
Know exactly what the verdict proves.
The companion guide explains PNG color types, explicit alpha versus tRNS, unused channels, white-matte fringes, batch checks, repair choices, and the final release gate.
- Original fixtures: real alpha, painted checkerboard, unused alpha, white edge, and indexed transparency
- Batch option: downloadable Python inspector with JSON output and CI exit codes
- Saved test record: eight passing synthetic assertions with explicit model-testing limits