Generated via Gemini Pro web UI with "Create image" tool enabled,
uploading a pure black (#000000) 1024x1024 image and prompting
"recreate this as it is". All images verified to contain SynthID
watermarks (confidence 0.52-0.67, carrier strength ~9300-9900).
These reference images are critical for carrier frequency discovery,
phase validation, and improving cross-resolution robustness.
