Emgu C# OpenCV: Make Color Black transparent

问题

I'm currently trying to implement a function with OpenCV which makes the color black of an image transparent. I used this thread as a guideline. Currently it is not working and I'm not sure if it is because of my transfer to C# or another mistake.

public Image<Bgr, Byte> BlackTransparent(Image<Bgr, Byte> image)
        {
            Mat imageMat = image.Mat;
            Mat finalMat = new Mat(imageMat.Rows, imageMat.Cols, Emgu.CV.CvEnum.DepthType.Cv8U, 4);
            Mat tmp = new Mat(imageMat.Rows, imageMat.Cols, Emgu.CV.CvEnum.DepthType.Cv8U, 1);
            Mat alpha = new Mat(imageMat.Rows, imageMat.Cols, Emgu.CV.CvEnum.DepthType.Cv8U, 1);

            CvInvoke.CvtColor(imageMat, tmp, Emgu.CV.CvEnum.ColorConversion.Bgr2Gray);
            CvInvoke.Threshold(tmp, alpha, 100, 255, Emgu.CV.CvEnum.ThresholdType.Binary);


            VectorOfMat rgb = new VectorOfMat(3);

            CvInvoke.Split(imageMat, rgb);

            Mat[] rgba = { rgb[0], rgb[1], rgb[2], alpha };

            VectorOfMat vector = new VectorOfMat(rgba);

            CvInvoke.Merge(vector, finalMat);

            return finalMat.ToImage<Bgr, Byte>();
        }

If anybody has an idea or suggestion I would appreciate it.

Bruno

回答1:

public Image<Bgra, Byte> BlackTransparent(Image<Bgr, Byte> image)
        {
            Mat imageMat = image.Mat;
            Mat finalMat = new Mat(imageMat.Rows, imageMat.Cols, Emgu.CV.CvEnum.DepthType.Cv8U, 4);
            Mat tmp = new Mat(imageMat.Rows, imageMat.Cols, Emgu.CV.CvEnum.DepthType.Cv8U, 1);
            Mat alpha = new Mat(imageMat.Rows, imageMat.Cols, Emgu.CV.CvEnum.DepthType.Cv8U, 1);

            CvInvoke.CvtColor(imageMat, tmp, Emgu.CV.CvEnum.ColorConversion.Bgr2Gray);
            CvInvoke.Threshold(tmp, alpha, 100, 255, Emgu.CV.CvEnum.ThresholdType.Binary);


            VectorOfMat rgb = new VectorOfMat(3);

            CvInvoke.Split(imageMat, rgb);

            Mat[] rgba = { rgb[0], rgb[1], rgb[2], alpha };

            VectorOfMat vector = new VectorOfMat(rgba);

            CvInvoke.Merge(vector, finalMat);

            return finalMat.ToImage<Bgra, Byte>();
        }

The return type of the function was wrong ... instead of the bgr colorspace it should be the bgra colorspace

来源：https://stackoverflow.com/questions/45660427/emgu-c-sharp-opencv-make-color-black-transparent