In the recipes of this chapter, you learned how to read and modify the pixel values of an image. The last recipe will teach you how to modify the appearance of an image by moving its pixels. The pixel values are not changed by this process; it is rather the position of each pixel that is remapped to a new location. This is useful in order to create special effects on an image or to correct image distortions caused, for example, by a lens.
In order to use the OpenCV remap function, you simply have to first define the map to be used in the remapping process. Second, you have to apply this map on an input image. Obviously, it is the way you define your map that will determine the effect that will be produced. In our example, we define a transformation function that will create a wavy effect on the image:
// remapping an image by creating wave effects
void wave(const cv::Mat &image, cv::Mat &result) {
// the map functions...