Plotting a Time Frequency contour/colormesh plot of a Discrete Wavelet Transform
With wavelets, that rely on scaling, you can expect time-scale, more than time-frequency. Obtained 2D images of scalograms from continuous wavelets is relatively easy. Most of them are not exactly invertible.
Exactly invertible discretized wavelets come in different shapes. To preserVe images with equal-sized pixels, you could prefer redundant discrete wavelets over DWT.
So, maybe rwt.rdwt()