Keep the received file
Keep a copy of the received file before editing it. Note its source and receipt date. If possible request the original: a screenshot is a different version.
Check the format
Atlas accepts JPG, PNG and WEBP up to 4 MB. If you must convert or resize a file, keep the initial version and record the change. Do not compare different versions as if they were identical.
Separate score and provenance
AI scores and Content Credentials answer different questions. A low score does not prove human origin. Missing credentials do not prove forgery. Keep the report and its limitations.