There a plenty of freely available map symbols to be found, but sometimes you need something unusual, not included in the normal map packs.

With drones everywhere, it's not hard to get aerial fotos of most things, but hyperrealistic 4k fotos do not really match most symbol sets. So I wondered, those of you who have created symbols before, do you apply any filters or whatnot other than just cropping out the needed part? And if so, what tools do you use? Photoshop? Gimp? Something else?

I thought I'd ask for some advice before blindly fumbling with filters I do not understand - I'm a complete noob at image editing.