Verify a prefix and decode a 600×300 two-color PNG

Use two-colors.png: left #0d9488, right #334155, dimensions 600×300. Compare a fictional field requiring a full Data URL with one requiring raw Base64.

1. Select the PNG in Image to Base64 and start conversion. The complete value should begin data:image/png;base64,.

2. Keep the whole value for a Data URL. For a raw field, take only the content after the first comma without removing the payload’s first character.

3. Restore the complete Data URL through Base64 to image and download the PNG. Inspect dimensions and halves; compare its checksum with the source for byte verification.

The complete form has a declaration and comma; raw Base64 has no data: declaration. Correct restoration is the same 600×300 two-color image. A long string alone does not establish that the receiving API accepted it.

A path, JSON quotation marks or an ellipsis is not the payload. Recover from the original output and split correctly. If the receiving contract requires an uploaded file, submit PNG rather than repeatedly modifying prefixes.
