Like translation , rotation may be employed in the early stages of more sophisticated image processing operations. Figure 1 A variable-direction edge detector. As an example, consider whose edges were detected by the directional operator defined using translation giving We can perform edge detection along the opposite direction to that shown in the image by employing a 180 degree rotation in the edge detection algorithm. The result is shown in Notice the slight degradation of this image due to rotation re-sampling. Interactive Experimentation You can interactively experiment with this operator by clicking here .
Exercises Consider images and which contain L-shaped parts of different sizes.
Make a collage based on a series of rotations and pixel additions of image You should begin by centering the propeller in the middle of the image. Next, rotate the image through a series of 45 degree rotations and add each rotated version back onto the original. Investigate the effects of re-sampling when using rotation as a preprocessing tool in an image erosion application. First erode the images and using a 90 degree directional erosion operator. Next, rotate the image through 90 degrees before applying the directional erosion operator along the 0 degree orientation.