You may try something like below.
private void GetPixel_Example(PaintEventArgs e)
{
Bitmap myBitmap = new Bitmap("Grapes.jpg");
Color pixelColor = myBitmap.GetPixel(50, 50);
SolidBrush pixelBrush = new SolidBrush(pixelColor);
e.Graphics.FillRectangle(pixelBrush, 0, 0, 100, 100);
}
For more info:
Bitmap.GetPixel Method
Pixel Coordinates
I hope this will help to you.