getting rgb value of a bmp on mouse move

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4.50/5 (2 votes)

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I want to get rgb value of the image on mouse move event in c sharp using aforge.net api.As when move mouse image then correspondingly it displays the rgb value of that point.
I want to do it using unmanaged image and pointer data. I dont have to use getpixel() method.kindly help me.below is my code.
thanks in advance

private void Form1_MouseMove(object sender, MouseEventArgs e)
        {
            // loading image
            Graphics g = CreateGraphics();
            Bitmap bmp = new Bitmap("bmpimage54.bmp");
            Rectangle r = new Rectangle(0, 0, bmp.Width, bmp.Height);
            g.DrawImage(bmp, r, r, GraphicsUnit.Pixel);
         // getting pixel values on mouse move

            Rectangle sourceRect = new Rectangle(0, 0, bmp.Width, bmp.Height);
            BitmapData imageData = bmp.LockBits(sourceRect,                    ImageLockMode.ReadWrite,PixelFormat.Format24bppRgb);
           UnmanagedImage unmanagedImage = new UnmanagedImage( imageData );
   unsafe
            {
                byte* imgPtr = (byte*)imageData.Scan0.ToPointer();
                byte* ptr;
                for (int i = 0; i < imageData.Height; i++)
                {
                    for (int j = 0; j < imageData.Width; j++)
                    {   
                        imgPtr += 3;
                    }
                    imgPtr += imageData.Stride - imageData.Width * 3;
                }
           }      
             bmp.UnlockBits(imageData);
        }

Posted 14-May-11 21:31pm

Member 7924798

Updated 22-Oct-18 16:45pm

Sergey Alexandrovich Kryukov

v3

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3 solutions

Solution 2

thank u abdur Rehman. It really solved my problem.

Posted 17-May-11 4:02am

Member 7924798

Comments

dontumindit 17-May-11 12:49pm

thnxxxxxxxxx

[no name] 18-May-11 9:32am

sorry it was by mistake. Now you can see it's fully rated.

Solution 3

BitmapData bd;

private void detection_pictureBox_MouseMove(object sender, MouseEventArgs e)
{
    if (detection_pictureBox.Image != null)
    {
        unsafe
        {
            byte* ptr = (byte*)bd.Scan0;
            int x = e.X * 3;
            int y = e.Y * bd.Stride;
            CurrPointerPos_lbl.Text = e.Location.ToString();
            CurrPointerCol_lbl.Text = ptr[x + y].ToString() + "," + ptr[x + y + 1].ToString() + "," + ptr[x + y + 2].ToString();
        }

    }
}

private void detection_pictureBox_MouseEnter(object sender, EventArgs e)
{
    if (detection_pictureBox.Image != null)
    {
        bd = (RunImgProcess.detectionImg).LockBits(new Rectangle(0, 0, RunImgProcess.detectionImg.Width, RunImgProcess.detectionImg.Height), ImageLockMode.ReadOnly, RunImgProcess.detectionImg.PixelFormat);
    }
}

private void detection_pictureBox_MouseLeave(object sender, EventArgs e)
{
    if (detection_pictureBox.Image != null)
    {
        (RunImgProcess.detectionImg).UnlockBits(bd);
    }
}

Posted 22-Oct-18 16:45pm

Member 14028901

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dontumindit · Accepted Answer · 2011-05-15T09:46:00

why u are applying loop?

once u know the co-ordinates, u can use indexing i.e square brackets to get the value of that particular color

i have loaded an image into picturebox, then using mouse move event of picture box

C#

private void pictureBox1_MouseMove(object sender, MouseEventArgs e)
{
     Bitmap bmp=new Bitmap(pictureBox1.Image);
     BitmapData bd=bmp.LockBits(new Rectangle(0,0,bmp.Width,bmp.Height),ImageLockMode.ReadOnly,PixelFormat.Format24bppRgb);

     unsafe
     {
         byte* ptr = (byte*)bd.Scan0;
         int x = e.X * 3;
         int y = e.Y * bd.Stride;
         label1.Text = e.Location.ToString();
         label2.Text = ptr[x + y].ToString() + "," + ptr[x + y + 1].ToString() + "," + ptr[x + y + 2].ToString();
     }
}

from cordinates, value of x,y is calculated, then x+y is used to reach the pixel location

x+y gives blue color value
x+y+1 gives green color value
x+y+2 gives red color value