There just needs to be reasonable effort put into it. Writing “hi” or drawing a line or some dots or just using the paint bucket tool to fill in the heart isn’t very much effort. You don’t need to make a masterpiece, you just need to spend more than 2 seconds on it.
Since the images sometimes don’t show, we like to have the picture to look at quickly, and also the link to the image that was put inside the image tags. The post would essentially be this: