getPixel() for loop

Posted by Weller Andrew Francis on
URL: http://imagej.273.s1.nabble.com/getPixel-for-loop-tp3702315.html

Dear all,

I am trying to determine the normalised variance of an image. For this I
need to minus the grey-level mean from each pixel's grey-level and
square this value. I figure the best way to do this is to determine each
pixel value by using getPixel() in a for loop.

My first question: is the initial (origin) pixel getPixel(0,0) or
getPixel(1,1)?

My second question: if I need to sum these values, how can I keep an
'updater' variable in my for-loop?

So for example, I have:

W = getWidth();
H = getHeight();
for (i=0; i<=H-1; i++) { // Presuming that the origin is 0,0
                                // else I guess for (i=1; i<=H; i++)?
        for (i=0; i<=W; i++) {
                p = getPixel(W,H);
                b = (p-mean)^2;
                SOME UPDATER HERE TO A SUM OF b
                }
        }
Once out of the loop, I can do things to the total.

Cheers, Andy