电子科发女学光电科学与工程学院 SCHOOL OF OPTOELECTRONIC SCIENCE AND ENGINEERING OF UESTC 10.2 Point,Line,and Edge Detection (1)First-order derivatives generally produce thicker edges in an image. (2)Second-order derivatives have a stronger response to fine detail,such as thin lines,isolated points. (3)Second-order derivatives produce a double-edge response at ramp and step transitions in intensity. (4)The sign of the second derivative 7 Isolated point can be used to determine whether a 5 transition into an edge is from light to 4 ● Ramp Line- Step 3 dark or dark to light. Flat segment 2 1 0 ● 1 mage strip5543210o06000013100007777- First derivative-1-1-1-1-1006-600012-2-100 Second derivative -10 000 1 0 6-12 6 00 11- 410.2 Point, Line, and Edge Detection (1) First-order derivatives generally produce thicker edges in an image. (2) Second-order derivatives have a stronger response to fine detail, such as thin lines, isolated points. (3) Second-order derivatives produce a double-edge response at ramp and step transitions in intensity. (4) The sign of the second derivative can be used to determine whether a transition into an edge is from light to dark or dark to light