Count the no of Black pixels in the image .

I get the Image after processing using the code below. Now i have to find the black pixels that are cracks

%%Load Image

i=imread('coor.jpg');
imshow(i);

%Image Adjust

adj=imadjust(i,stretchlim(i));
imshow(adj);

%%Convert RGB to Gray

gry=rgb2gray(adj);
imshow(gry,[]);

%%Image segementation by thresholding

level=0.09;
thres=im2bw(gry,level);
imshow(thres);

% Image morphological operation

bw=bwmorph(thres,'clean',20);
imshow(bw);

%%End

Answer 1

[Walter Roberson]

sum(bw(:) == 0)

[MJ Thangaraj]

What if i have to find the WHITE pixels

[Walter Roberson]

sum(bw(:))

or

nnz(bw)