private URL doGetImageURL(String srcString) {

			HTMLDocument htmlDocument = (HTMLDocument) getDocument();
			URL context = htmlDocument.getBase();
			try {
				URL url = new URL(context, srcString);
				if (FileUtilities.exists(url.toURI())) {
					// it's a good one, let it through
					return url;
				}
			}
			catch (MalformedURLException | URISyntaxException e) {
				// check below
			}

			// Try the ResourceManager.  This will work for images that start with GHelp
			// relative link syntax such as 'help/', 'help/topics/' and 'images/'
			URL resource = ResourceManager.getResource(srcString);
			return resource;
		}
Overridden to allow us to find images that are defined as constants in places like
{@link Icons}
Ghidra/Framework/Help/src/main/java/help/GHelpHTMLEditorKit.java