protected Image getOldImage(File helpTopicDir, String imageName) {
		if (helpTopicDir == null) {
			throw new AssertException("Invalid help topic name - null");
		}

		File imageFile = new File(helpTopicDir, "/images/" + imageName);
		if (!imageFile.exists()) {
//			throw new AssertException("Cannot find image " + imageName + " in help topic " +
//				helpTopicDir);
			return createEmptyImage(10, 10);
		}

		return readImage(imageFile);
	}
Call when you are finished generating a new image.  This method will either show the
newly created image or write it to disk, depending upon the value of
{@link #SAVE_CREATED_IMAGE_FILE}, which is a system property.

@param helpTopic The help topic that contains the image
@param oldImageName  The name of the image
Ghidra/Features/Base/src/main/java/help/screenshot/GhidraScreenShotGenerator.java