There is probably a better way but you could make a bunch of copies of the image, shift the hue in GIMP (or whatever image editor you prefer) until you end up with an amount of images equal to the total number of changes you want throughout the day, put them all in a directory, go to set that directory as your wallpaper image, make it a slideshow and set the timer to change however often you want the shift to happen.

If you were trying to make a specific color match a specific time of day, it would not work, unless you set the wallpaper after each reboot to the appropriate color. It also would be a bit tedious if you wanted a large number of hue changes throughout the day.

I use [Plasma Wallpapers Dynamic](https://github.com/zzag/plasma5-wallpapers-dynamic) . Instead though I set it up where it changes some scene every few hours to match daylight conditions, but you could accomplish exactly what you are asking – you just have to provide the actual wallpaper file for each hue and then specify what time for when you build the background

I know there is a plugin that allows glsl shaders as plasma live wallpapers and I bet you could make some sort of shader that just changes hue of the texture over time if one doesn't already exsist.

I was about to date myself and say "there's probably a dcop interface exposed"... But there's probably a dbus interface exposed. You could write a script and plug it into a cron job or similar to tell it to adjust the background every hour or so. There are some nice dbus exploration tools available so you can discover the correct call to make.

If that doesn't work, the hue is probably stored in a human readable file somewhere in your .config folder. You could probably have a script adjust the value in the file directly. Might take plasma a little while to notice, but it likely will.