A three-partial tone (440 + 880 + 1760 Hz) rendered four ways — the four-panel specshow layout: linear-frequency STFT, log-frequency STFT, mel spectrogram, chromagram. The proof is in the axis mapping: in log mode the pixel-row distance 440→880 must equal 880→1760 (octaves equidistant, ±2 px), while in linear mode 880→1760 must be 2× the 440→880 distance. Peak rows are found from the actual STFT argmax bins, mapped with the same functions that draw the pixels, then pixel-probed for brightness. Axis ticks are cross-checked against fft_frequencies / frames_to_time. All numerics node-verified.