Hi !
NET is in anniversary mode, so I think it will be a good idea to share some camera samples in C#. For these demos I’m using C#, NET 6 and OpenCVSharp as OpenCV wrapper for .NET.
Today post: detect a face using haar cascades and blur the face area. This demo also show the detected face in a separated window (just for fun).
Easy to implement, and also easy to read:
Blurring a Face 😀 also in C# using .NET 6.
— El Bruno 🐿️🐺⚡ (we don't talk about me 🤐) (@elbruno) February 15, 2022
Blog post coming soon #dotNETLovesMe pic.twitter.com/k0PA0b1w87
Code Sample
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| // 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; | |
| } | |
| } | |
| } |
Important: Haar cascades are easy to implement and learn, however, not recommented as a good solution to detect faces.
El Bruno 