On Mac OS (with PlantUML installed via Homebrew), PNGs are always generated with a DPI (in metadata) of 72.
Setting "skinparam dpi 150" (for example) renders an image with the correct number of pixels, but the PNG metadata still says 72 DPI, so images aren't display properly in Quicklook, Preview, etc.
The same thing happens when running the PUML server via Docker, so I don't think it's a problem with my environment.
