#OpenCV – Detect and blur faces 😁 using haar cascades in C#

// Copyright (c) 2022 // Author : Bruno Capuano // Create Time : 2022 Feb // Change Log : // - Open a camera feed from a local USB webcam and analyze each frame to detect faces using haar cascades // - When a face is detected, the app will blur the face zone in the main window // - When a face is detected, the app will show the original detected face in a separated window // - Press [F] to enable / disable the face detection process // - Press [Q] to quit the app // // The MIT License (MIT) // // Permission is hereby granted, free of charge, to any person obtaining a copy // of this software and associated documentation files (the "Software"), to deal // in the Software without restriction, including without limitation the rights // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell // copies of the Software, and to permit persons to whom the Software is // furnished to do so, subject to the following conditions: // // The above copyright notice and this permission notice shall be included in // all copies or substantial portions of the Software. // // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN // THE SOFTWARE.

using OpenCvSharp;

var faceCascade = new CascadeClassifier(); faceCascade.Load("haarcascade_frontalface_default.xml");

using var capture = new VideoCapture(0); { var image = new Mat(); var showFace = true; var run = true; using var window = new Window("El Bruno - Blur Face"); using var windowFace = new Window("El Bruno - Face");

while (run) { capture.Read(image); if (image.Empty()) break;

var newSize = new Size(640, 480); using var smallFrame = new Mat(); Cv2.Resize(image, smallFrame, newSize);

if (showFace) { using var gray = new Mat(); Cv2.CvtColor(smallFrame, gray, ColorConversionCodes.BGR2GRAY);

var faces = faceCascade.DetectMultiScale(gray, 1.3, 5); foreach (var face in faces) { Cv2.Rectangle(smallFrame, face, Scalar.Red);

// create a new Mat with the detected face var faceImg = new Mat(smallFrame, new OpenCvSharp.Range(face.Top, face.Top + face.Width), new OpenCvSharp.Range(face.Left, face.Left + face.Height)); windowFace.Image = faceImg;

// blur the face area in the original frame var faceBlur = new Mat(); Cv2.GaussianBlur(faceImg, faceBlur, new Size(23, 23), 30); smallFrame[face] = faceBlur; } }

window.Image = smallFrame; switch ((char)Cv2.WaitKey(100)) { case (char)27: // ESC run = false; break; case 'f': showFace = !showFace; break; } } }