I'm working on a map where I'm overlaying a topographic map on a hillshade map (from ALS data). With the right levels of transparency, those maps tend to be the best base for all kinds of stuff.
However, it appears that my topographic map (that already includes some very light hillshading) has areas that should be white, defined as transparent. So at those, the hillshade data below will always stick out in their pure gray.
(shown here with the topo map with no transparency, to highlight the issue)
How do I set transparent to be white?
Most stuff I find online, is about the reverse, setting a color to transparent, and when it's the other way round, it appears to not work with my data, e.g. the method shown at Setting multiple colors transparent in raster map in ArcMap?
Perhaps it also depends on what kind of raster I have.