c# - True pixel quantity -

i know question littel strange need realy help. have algorithme calculate true pixel quantity in binary image. example how work:

binary image :

0 0 1 0 0 1 1 1 1 1 0 1   1 1 1 1 1 1 1 1 0 0 0 1 0 1 0 0 0 1 

her result :

18 15 11 8 6 5 16 13 9  7 5 4 11 9  6  5 4 3 5  4  2  2 2 2 2  2  1  1 1 1 

and how work :

result (i,j) = result (i+1, j) + result (i, j+1) - result(i + 1, j + 1) + image(i,j) 

her example 18 value:

18 = 16 + 15 - 13 + 0  

my question : name of algorithm because need more information it?

thank help.

this called integral image, or summed area table. used speedup box filtering, among others. 2d generalization of prefix sum.