Histogram stretch and overlay of other rasters

Continuing the discussion from this [post](https://discourse.julialang.org/t/how-to-create-a-rgb-plot-from-three-different-tif-files/92001/13).

The bright dots in the following image are targets, the low Rayleigh corrected reflectances values are expected since land was masked out and water absorbs most of the radiation.

According to this [tutorial](https://www.generic-mapping-tools.org/GMTjl_doc/tutorials/Landsat8/histogram_stretch/), I used `histogram(Ir_img, auto=true, bin=10, show=true)` to find good stretch points

I used `imshow(Ir_img, stretch=[0 100])`, didn't notice any difference on the Ir_img plot and receive this warning `the following options were not consumed in grdimage => [:stretch]`.

I am trying to reduce the darkness of the water in the RGB image.

Also, is it possible to overlay a fourth raster on the RGB plot? If not, is this a future feature?