Inrange method is invalid for cropped images

[Jakvic]

Summary of your issue

Inrange method is useless for the image that use DrawImage method

Environment

win10+vs2017+opencvsharp4.0.0

Example code:

paste your core code
`
using OpenCvSharp;
using OpenCvSharp.Extensions;
using static OpenCvSharp.Cv2;
using System.Drawing;
namespace RcoloR
{
    class Program
    {
        static Bitmap Mybmp = new Bitmap("E:/CVIMG/lenna.png");
        static void Main(string[] args)
        {
            using (new Window("SRC", WindowMode.Normal, Mybmp.ToMat())) ;   //source image

            Prtsc(Mybmp, out Bitmap dst);  //crop image           
            using (new Window("IMAGE_CUT", WindowMode.Normal, dst.ToMat())) ; //show the cropped image

            MyInrange(dst,out Bitmap dstbmp);   // Inrange 
            using (new Window("DST", WindowMode.Normal, dstbmp.ToMat()));  //show the inranged image

            WaitKey();
        }
        static void Prtsc(Bitmap src, out Bitmap dst)  // crop image
        {
            dst = new Bitmap(300,300);
            using (Graphics g = Graphics.FromImage(dst))
            {
                g.DrawImage(src,new Rectangle(0,0,300,300),new Rectangle(0,0,300,300),GraphicsUnit.Pixel);
            }
        }
        static void MyInrange(Bitmap bmpsrc,out Bitmap dstbmp) // Cv2.Inrange();
        {
            using (Mat src = BitmapConverter.ToMat(bmpsrc))
            using (Mat dst = new Mat())
            {
                Scalar low_value = new Scalar(100, 100, 100);
                Scalar high_value = new Scalar(255, 255, 255);
                InRange(src, low_value, high_value, dst);
                dstbmp = dst.ToBitmap();
            }
        }
    }
}
`

## Output:

paste your output

[shimat]

The cause of this issue is Bitmap PixelFormat value that is not intended for you.

• Mybmp.PixelFormat: Format24bppRgb
• dst.PixelFormat: Format32bppArgb

So, the Type() of dst.ToMat() is not 8UC3 but 8UC4, and the result of InRange is unintended.

[Jakvic]

Hi,Sorry to reply you so late,i find the solution

dst = new Bitmap(300,300,System.Drawing.Imaging.PixelFormat.Format24bppRgb);

Just change this row,it's ok; Thanks a lot ,love you so much;