Is it possible to combine the values from two rasters? I.e. raster math client side

**Is your feature request related to a problem? Please describe.**
This feature request is not related to a problem.

**Describe the solution you'd like**
We would like to be able to perform things like image differencing client side - subtracting the pixel values of one raster from another, and displaying the results.

**Describe alternatives you've considered**
We have tried implementing the server side.

**Additional context**
We are also using georaster-layer-for-leaflet, and are very grateful for this awesome project.