Learning OpenCV

Exercises

1. This chapter completes our introduction to basic I/O programming and data structures in OpenCV. The following exercises build on this knowledge and create useful utilities for later use.

   1. Create a program that (1) reads frames from a video, (2) turns the result to grayscale, and (3) performs Canny edge detection on the image. Display all three stages of processing in three different windows, with each window appropriately named for its function.

   2. Display all three stages of processing in one image.

      Hint: Create another image of the same height but three times the width as the video frame. Copy the images into this, either by using pointers or (more cleverly) by creating three new image headers that point to the beginning of and to one-third and two-thirds of the way into the imageData. Then use cvCopy().

   3. Write appropriate text labels describing the processing in each of the three slots.

2. Create a program that reads in and displays an image. When the user's mouse clicks on the image, read in the corresponding pixel (blue, green, red) values and write those values as text to the screen at the mouse location.

   1. For the program of exercise 1b, display the mouse coordinates of the individual image when clicking anywhere within the three-image display.

3. Create a program that reads in and displays an image.

   1. Allow the user to select a rectangular region in the image by drawing a rectangle with the mouse button held down, and highlight the region when the mouse button is released. Be careful ...