Algorithm to find repeated pixel values in an image

Hello friends! I need to build an algorithm that finds similar intensity valued pixels in an image.For example,the intensities within the range of 25-27 need to be identified in an image.What will be the efficient algorithm ?

Answer 1

[Doug Hull]

im = imread('pout.tif');
vi = (im > 60) & (im < 80);
imshow(vi)

Answer 2

[Image Analyst]

Doug's method is exactly what I would have given for a grayscale image. I don't know if you have a color image but the question is not so clear in the case of a color image since there are 3 "intensities" in a 3 color image, plus some other definitions of intensity if you go to other color spaces (like my avatar). In that case, see my File Exchange particularly the Delta E demo. Delta E is a color difference.