How to get pixels?

I am trying to understand a program. I get stuck in a line I(x,y)<25

I understand I is an image and x and y are the coordinates of a point in the image. But what does 25 mean? Is it the number of pixels?

Answer 1

[KSSV]

I is an image data obtained by using imread. I feel in the code already using find some pixels are obtained, and (x,y) are those positions. Out of these positions, I(x,y)<25, seeks the pixel values less than 25.