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  • Book Overview & Buying Mastering OpenCV with Practical Computer Vision Projects
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Mastering OpenCV with Practical Computer Vision Projects

Mastering OpenCV with Practical Computer Vision Projects

4.2 (17)
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Mastering OpenCV with Practical Computer Vision Projects

Mastering OpenCV with Practical Computer Vision Projects

4.2 (17)

Overview of this book

Computer Vision is fast becoming an important technology and is used in Mars robots, national security systems, automated factories, driver-less cars, and medical image analysis to new forms of human-computer interaction. OpenCV is the most common library for computer vision, providing hundreds of complex and fast algorithms. But it has a steep learning curve and limited in-depth tutorials.Mastering OpenCV with Practical Computer Vision Projects is the perfect book for developers with just basic OpenCV skills who want to try practical computer vision projects, as well as the seasoned OpenCV experts who want to add more Computer Vision topics to their skill set or gain more experience with OpenCV's new C++ interface before migrating from the C API to the C++ API.Each chapter is a separate project including the necessary background knowledge, so try them all one-by-one or jump straight to the projects you're most interested in.Create working prototypes from this book including real-time mobile apps, Augmented Reality, 3D shape from video, or track faces & eyes, fluid wall using Kinect, number plate recognition and so on. Mastering OpenCV with Practical Computer Vision Projects gives you rapid training in nine computer vision areas with useful projects.
Table of Contents (15 chapters)
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Mastering OpenCV with Practical Computer Vision Projects
Credits
About the Authors
About the Reviewers
www.PacktPub.com
Preface
1
Index

Generating an "evil" mode using edge filters


Cartoons and comics always have both good and bad characters. With the right combination of edge filters, a scary image can be generated from the most innocent-looking people! The trick is to use a small-edge filter that will find many edges all over the image, then merge the edges using a small Median filter.

We will perform this on a grayscale image with some noise reduction, so the previous code for converting the original image to grayscale and applying a 7 x 7 Median filter should be used again (the first image in the following figure shows the output of the grayscale Median blur). Instead of following it with a Laplacian filter and Binary threshold, we can get a scarier look if we apply a 3 x 3 Scharr gradient filter along x and y (the second image in the figure), and then apply a binary threshold with a very low cutoff (the third image in the figure) and a 3 x 3 Median blur, producing the final "evil" mask (the fourth image in the figure):

Mat gray;
cvtColor(srcColor, gray, CV_BGR2GRAY);
const int MEDIAN_BLUR_FILTER_SIZE = 7;
medianBlur(gray, gray, MEDIAN_BLUR_FILTER_SIZE);
Mat edges, edges2;
Scharr(srcGray, edges, CV_8U, 1, 0);
Scharr(srcGray, edges2, CV_8U, 1, 0, -1);
edges += edges2;     // Combine the x & y edges together.
const int EVIL_EDGE_THRESHOLD = 12;
threshold(edges, mask, EVIL_EDGE_THRESHOLD, 255, THRESH_BINARY_INV);
medianBlur(mask, mask, 3);

Now that we have an "evil" mask, we can overlay this mask onto the cartoonified "painting" image like we did with the regular "sketch" edge mask. The final result is shown on the right side of the following figure:

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