Contours and Edge Detection with OpenCV in C#

[@ProgrammingWithChris]

Hi, thanks for watching! Let me know what OpenCV topics you'd like me to cover in future videos. Enjoy! 🕘Timestamps: 0:00 - Video Start 0:52 - What is an Edge in image processing? 1:48 - Introduction to the Sobel Operators in OpenCV 9:32 - Canny Edge Detection in OpenCV 16:58 - Contours in OpenCV 24:48 - How to draw contours on your image 26:37 - How to fill a contour with color in OpenCV 27:55 - What's next in the series

[@TheLordOfWolves]

Godlike, you are a life saver brother!

[@ProgrammingWithChris]

Haha! Glad I could help out.

[@TheLordOfWolves]

@@ProgrammingWithChris can this be applied to video ?

[@ProgrammingWithChris]

@@TheLordOfWolves Yup, definitely. You just have to apply the same steps to each frame in a loop from the Video Capture device. I have a video on, well, VideoCapture with OpenCV in this playlist as well, if that helps at all!

[@cissemy]

Thanks Chris How to build a document scanning app using OpenCv in C# ?

[@cissemy]

Thanks I am getting : System.TypeInitializationException: 'The type initializer for 'Emgu.CV.CvInvoke' threw an exception.' DllNotFoundException: Unable to load DLL 'cvextern' or one of its dependencies: The specified module could not be found. (0x8007007E)

[@jessepezza2865]

Hey Chris, great videos so far! I was hoping you or anyone else might be able to help me figure out this error I'm getting when trying to do the FindContours portion. This is what I'm getting: Emgu.CV.Util.CvException HResult=0x80131500 Message=OpenCV: (_contours.kind() == _InputArray::STD_VECTOR_VECTOR || _contours.kind() == _InputArray::STD_VECTOR_MAT || _contours.kind() == _InputArray::STD_VECTOR_UMAT) Source=Emgu.CV StackTrace: at Emgu.CV.CvInvoke.CvErrorHandler(Int32 status, IntPtr funcName, IntPtr errMsg, IntPtr fileName, Int32 line, IntPtr userData) at Emgu.CV.CvInvoke.cveFindContours(IntPtr image, IntPtr contours, IntPtr hierarchy, RetrType mode, ChainApproxMethod method, Point& offset) at Emgu.CV.CvInvoke.FindContours(IInputOutputArray image, IOutputArray contours, IOutputArray hierarchy, RetrType mode, ChainApproxMethod method, Point offset) at EmguCV_Basic_01.Program.Main() in C:\Users\myname\Documents\myname\Coding Practice\SoloLearn\EmguCV Basic 01\EmguCV Basic 01\Program.cs:line 151 Here's the line in question. Doesn't seem like anything differs from yours, but maybe I'm just not seeing it: CvInvoke.FindContours(thresholdPic, contours, heirarchy, Emgu.CV.CvEnum.RetrType.Tree, Emgu.CV.CvEnum.ChainApproxMethod.ChainApproxNone); Any ideas?

[@jessepezza2865]

Nevermind, found it! My contours variable was using the class VectorOfPoint instead of VectorOfVectorOfPoint lol.