find the bounding box of some points randomly located in a bitmap image from C# VS2013

Question

I have a bitmap image where some points are located on it. Each point has a pair of coordinates (x, y) on the bitmap image (a jpeg file).

I need to find the bounding box of the points (NOT the image) so that I can specify a rectangle that cover the regions with the points such that

The region left bound = minimal x of all points
The region right bound = maximal x of all points
The region top bound = minimal y of all points
The region bottom bound = maximal y of all points

The solution here How to remove a border with an unknown width from an image does not work for me because it is for finding a rectangular region inside an image. I have some randomly located points on the image.

The solution here Getting the bounding box of a vector of points? does not work for me either because the coordinates of points have been transformed in th ebitmap image.

My C# code in VS2013:

 System.Drawing.Bitmap canvasImage = new System.Drawing.Bitmap(12 * 64 - (2 * 4),  15 * 64 - ( 5 * 64), System.Drawing.Imaging.PixelFormat.Format32bppArgb);

Graphics g = Graphics.FromImage(canvasImage);

   var xr = Enumerable.Range( 2 , 12 );
   var yr = Enumerable.Range( 5 , 15 );
   foreach (int x in xr)
        {
            foreach (int y in yr)
            {
                int[] imageCornerXY = new int[4];
                System.Drawing.Bitmap tempImage = … // a function generate an image

                g.DrawImage(tempImage, new System.Drawing.PointF(x * 256 - (startX * 256), y * 256 - (startY * 256)));
            }
        }
   // the image bounds have: top : 0  , bottom: 640, west: 0 east: 760
   RectangleF imageBounds = canvasImage.GetBounds();

  // Suppose that I have some points located in the region of (minCornerX, minCornerY), and (maxCornerX, maxCornerY), how to copy them to a new image and their relative locations are not changed ? 

  Rectangle rect = new Rectangle( minCornerX, minCornerY, maxCornerX - minCornerX  ,  minCornerY - minCornerY);
   // I need to copy the region covered by this rectangle to a new image.
    Bitmap newMapImage = copyImage(canvasImage, rect);

My code just make a copy of an empty image except that I increase the size of rect to cover a large region. But, I just need a bounding box to cover the points exactly without any margins.

Any help would be appreciated.

Find the minima and the maxima of the x and the y coordinates. Would be four lines of Linq if you store the points in a suitable structure.. — TaW, Oct 13 '15 at 21:14
The points loaded from a file with latitude and longitude are stored in a list. They are transformed to pixels and then tile pixels. — user3601704, Oct 13 '15 at 21:22
The problem is that if the tile pixels coordinates cannot be directly used as coordinates in the bitmap image. — user3601704, Oct 13 '15 at 21:24

find the bounding box of some points randomly located in a bitmap image from C# VS2013

0 Answers0