How can I convert Mat to Bitmap using OpenCVSharp?

Question

First, I tried this,

    public static Bitmap MatToBitmap(Mat mat)
    {
        return OpenCvSharp.Extensions.BitmapConverter.ToBitmap(mat);
    }

So, then, I tried this,

    public static Bitmap MatToBitmap(Mat mat)
    {
        mat.ConvertTo(mat, MatType.CV_8U);
        return OpenCvSharp.Extensions.BitmapConverter.ToBitmap(mat);
    }

The image is completely black,

    public static Bitmap ConvertMatToBitmap(Mat matToConvert) 
    {            
        return new Bitmap(matToConvert.Cols, matToConvert.Rows, 4*matToConvert.Rows, System.Drawing.Imaging.PixelFormat.Format8bppIndexed, matToConvert.Data);
    }

This doesn't work either.

Answer 1

Instead of using Mat type, I suggest you to use IplImage type. Take the following example code as reference (I use VisualStudio2013 with OpenCvSharp2):

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using OpenCvSharp;
using System.Drawing;

namespace TestOpenCVSharp
{
    class Program
    {
        static void Main(string[] args)
        {
            // Read the Lenna image
            IplImage inputImage = new IplImage(@"Lenna.png");

            // Display the input image for visual inspection
            new CvWindow("original image", inputImage);
            Cv.WaitKey();

            // Convert into bitmap
            Bitmap bitimg = MatToBitmap(img);                
            // Save the bitmap
            bitimg.Save(@"bitmap.png");
        } // end of main function

        // This is the function that converts IplImage image
        // into Bitmap
        public static Bitmap MatToBitmap(IplImage image)
        {
            return OpenCvSharp.Extensions.BitmapConverter.ToBitmap(image);
        } // end of MatToBitmap function
    } // end of class definition
}  // end of namespace definition

This is your input Lenna image:

And this is the bitmap.png that is created from Bitmap type:

Hope it helps!

Update:

By using OpenCVSharp3, the following code can also convert a Mat type into Bitmap type:

Mat image = new Mat(@"Lenna.png");
Cv2.ImShow("image", image);
Cv2.WaitKey();

Bitmap bitimg = MatToBitmap(image);
// Save the bitmap
bitimg.Save(@"bitmap.png");

with the function:

public static Bitmap MatToBitmap(Mat image)
{
   return OpenCvSharp.Extensions.BitmapConverter.ToBitmap(image);
} // end of MatToBitmap function

And the obtained result is the same as shown above.