This photo of Lena (Lenna) Söderberg is the most widely used test image for computer vision applications. I have made a conscious decision to use this image for examples on this webpage. We should be respectful of the woman in the photo and know how this image came to be. Read about the photo at The Lenna story.
All the code in the computer vision examples uses OpenCV. The OpenCV homepage is opencv.org; you’ll want to look at their reference manual and tutorials, in particular tutorials about installation.