find distance from center pixel to next white pixel

How can I find the center pixel in a normal window like 640 by 480 pixels..I attached my one reference image from this image I want to measure h1, h2, w1, w2 from this mid point.Is it possible to measure the unknown shape of images?

[Rik]

You can generate a distance grid with the code below. Using find, you can find what you define as a high intensity pixel.

x_center=320;
y_center=240;
[X,Y]=meshgrid((1:640)-x_center,(1:480)-y_center);
distance_to_center=hypot(X,Y);

[Rik]

You can find the center point of a blob with regionprops:

stats = regionprops(your_binary_image);
centroid = stats.centroid;

Then you should be able to use find on the relevant row and column to find the outer edges of your shape.