The middle panel shows an image processing effect known as edge enhancement, while the last panel uses an effect called edge detection. Most graphics software has filters that do these operations. Slight levels of edge enhancement (less obvious than what I used in the middle panel) can often make a photographic image look "sharper" and superficially more pleasing to the eye. If you look closely however, you can see the sort of artificial effects introduced around the edges of objects (as seen here quite obviously). So to people who know about it, edge enhancement is often considered a distraction rather than an improvement.

This is important for modern digital images, such as those found on DVDs. Some production studios apply edge enhancement to the film frames, believing that the audience will prefer a sharper image. One good quality home theatre equipment, this effect can often be seen and can be an annoying distraction from the film viewing experience. If you ever see a DVD image that looks "unreal" or "too sharp to be true", particularly where there is a sharp edge between foreground characters and background scenery, then you will see why edge enhancement is not always a good thing.