Why Edge Detection Is A Non-trivial Task
To illustrate why edge detection is not a trivial task, consider the problem of detecting edges in the following one-dimensional signal. Here, we may intuitively say that there should be an edge between the 4th and 5th pixels.
| 5 | 7 | 6 | 4 | 152 | 148 | 149 |
If the intensity difference were smaller between the 4th and the 5th pixels and if the intensity differences between the adjacent neighboring pixels were higher, it would not be as easy to say that there should be an edge in the corresponding region. Moreover, one could argue that this case is one in which there are several edges.
| 5 | 7 | 6 | 41 | 113 | 148 | 149 |
Hence, to firmly state a specific threshold on how large the intensity change between two neighbouring pixels must be for us to say that there should be an edge between these pixels is not always simple. Indeed, this is one of the reasons why edge detection may be a non-trivial problem unless the objects in the scene are particularly simple and the illumination conditions can be well controlled (see for example, the edges extracted from the image with the girl above).
Read more about this topic: Edge Detection
Famous quotes containing the words edge and/or task:
“My Turn is the distilled bathwater of Mrs. Reagan’s life. It is for the most part sweetish, with a tart edge of rebuke, but disappointingly free of dirt or particulate matter of any kind.”
—Barbara Ehrenreich (b. 1941)
“Your children are not here to fill the void left by marital dissatisfaction and disengagement. They are not to be utilized as a substitute for adult-adult intimacy. They are not in this world in order to satisfy a wife’s or a husband’s need for love, closeness or a sense of worth. A child’s task is to fully develop his/her emerging self. When we place our children in the position of satisfying our needs, we rob them of their childhood.”
—Aaron Hess (20th century)