unable to load cvextern in a c# project

i'm trying to debug my program, using emgu and HaarCascade in c#. i'm getting an exception like so :

Unable to load DLL 'cvextern': The specified module could not be found. (Exception from HRESULT: 0x8007007E)

i've added the file cvextern.dll to my project and tried both "copy always" and "copy if newer" options on the properties of the file. also, the build is in platform x64.

here's partly what i wrote :

    private void Load_Click(object sender, EventArgs e)
    {
        OpenFileDialog dlg = new OpenFileDialog();
        dlg.Filter = "Photo Files (*.jpg)|*.JPG";
        dlg.CheckFileExists = true;
        if (dlg.ShowDialog() == DialogResult.OK)
        {
            Image<Bgr, Byte> My_Image = new Image<Bgr, byte>(dlg.FileName);
            HaarCascade face = new HaarCascade("haarcascade_frontalface_alt.xml");

and the exception is in the last line.

The error your receiving is not solely down to cvextern this dll actually points to almost all of the other opencv dlls and all are required. With this error you will require the following dll in your project.

Note that the "220" is the version number this will change according to updates.

cudart64_32_16.dll
cufft64_32_16.dll
cvextern.dll
npp64_32_16.dll
opencv_calib3d220.dll
opencv_contrib220.dll
opencv_core220.dll
opencv_features2d220.dll
opencv_flann220.dll
opencv_gpu220.dll
opencv_highgui220.dll
opencv_imgproc220.dll
opencv_legacy220.dll
opencv_ml220.dll
opencv_objdetect220.dll
opencv_video220.dll

This error is covered along with others in my article on codeproject here.

Any other problems let me know,

Cheers,

Chris

gyukov

This error popped up on my side with Emgu CV 3.1 and I found for this issue a following working solution:

copy the cvextern.dll in the application directory \bin\Debug\

Hope this helps.

for version 2.3 it`s list increases with opencv_ffmpeg.dll and opencv_flann231.dll.

The cvextern.dll should be in Windows\System32 for x86 and Windows\SysWOW64 for x64 it's work for me. ps: i used NuGet Package 'EmguCV' v3.1.0.1 with VS2015

My problem for this error was that VS2015 was running the web project in 32 bit IIS Express. The fix was to ensure it was using 64 bit IIS Express

I added this code at startup to remind myself when setting up a new machine

if (IntPtr.Size != 8)
{
     throw new Exception("Change VS options to ensure 64bit IIS Express");
}

in my case I had switched to a 64 target and not noticed, going to x86 made this go away

来源：https://stackoverflow.com/questions/8028523/unable-to-load-cvextern-in-a-c-sharp-project

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