Finding pixels having a specific intensity value

Hi, I want to find the pixels or the infinitesimal areas having an intensity value of 255 in a grayscaled image and calculate the area they occupy in the image. Can anyone help me?

Answer 1

[Image Analyst]

To "find the pixels", as in getting the rows and columns where they live , do this:

[rows, columns] = find(grayImage == 255);

To get the area in pixels, use the formula like Walter gave.

Answer 2

[Walter Roberson]

Area255 = sum(GrayMatrix(:)==255);

This presumes that each pixel contributes 1 square unit of area. If you are working with projective maps that would not be true, naturally.