This would allow the client to utilize different color mappings to visualize the spectrogram instead of only the default one.

• Back-end spectrogram generation should swap from having a colorplot to being grayscale
• Utilize d3 color schemes to map the grayscale colors to a new color scheme using d3: https://observablehq.com/@d3/color-schemes. You'll notice in the d3 schemes you have matplotlib schemes like Plasma, Inferno, Warm, Turbo. May want to be able to select a default 0 value color as well, that way you can have black backgrounds with a color scheme.
• Have a dropdown of several named color schemes
• Using the scheme you should be able to use JS to create a canvas object, read in the image data and modify the colors and return back a JS Image() object that can be passed to geoJS to render using the newer color scheme.