English: The result of a constant-Q transform applied to the waveform of a C major chord played on a piano. The x axis corresponds to frequency mapped to the standard pitch names (increasing from lower pitches on the left to higher frequencies on the right). The y axis is time, with the start of the piano chord happening at the bottom and the release happening at the top (approximately 8 seconds later)

The darker areas correspond to higher values of the constant Q transform. The peak values are vibrating frequencies of the strings. The leftmost 3 strongest peaks are at the fundamental frequencies of the notes of the C major chord (C, E, G). The the remaining peaks to the right of the fundamental frequencies are overtones.

Note that Brown-Puckette algorithm on the showcqt uses kernels derived directly from frequency domain, the bandwidth calculation is actually variable-Q, and showcqt uses linear/nth root amplitude scaling rather than logarithmic.