This page (and its attendant calculator) was designed to automatically calculate the square footage of irregular items such as the deck area of an Iowa-class Battleship for more accurate estimates of the probability of hitting them with aerial bombs.

HOW IT WORKS

First, you find a top down drawing and then flood fill the deck area with Red (#ff0000) (R255, G0, B0) after you invert your selection area to create an image similar to these:

You then LOAD the image in the console box below, enter the known width (in the case of an Iowa class BB, some 887 feet OAL.) in the KNOWN DIMENSION input box, and then click on CALCULATE FOOTAGE.

The program automatically rescales the image so that the pixel width is equal to the known dimension at the same ratio, enabling a rough 1:1 ratio between 1 pixel and 1 square unit of whatever measurement you entered (foot or meter). It then iterates through the image, counting every pixel that matches (#ff0000) (R255, G0, B0) and returns the results to you.