Counting the number of black pixels in an image

Hello, I need help counting the number of black pixels in an image that was just taken through a camera. My current program is able to take an image and then convert the image into a black and white image based on the colors in the first image. I need to count the amount of black pixels in the processed image that was just taken that only contains black and white pixels. If it helps, here is my code so far (P.S. This includes some code that I have commented out to get the program working to this point):

clc
clear
clear all
images= []
webcamlist()
cam= webcam(1)
preview(cam)

pause(2);

images= snapshot(cam)
imshow(images)
r_channel= images(:,:,1);
g_channel= images(:,:,2);
b_channel= images(:,:,3);
images(:,:,1) =0;
images(:,:,3) = 0;
image(images);
mask= g_channel > 100, b_channel > 800, r_channel < 800, b_channel < 0, r_channel < 0;
imshow(mask)
 gr_ratio = double(g_channel)./double(r_channel);
 gb_ratio = double(g_channel)./double(b_channel);
 rb_ratio = double(r_channel)./double(b_channel);
 
% gr_ratio(isnan(g_ratio))=0;
% grayImage = rgb2gray(image);
% binaryImage = grayImage > 20;
% binaryImage = bwareaopen(binaryImage, 50);
% binaryImage = imfill(binaryImage, 'holes');
% grayImage(~binaryImage) = 0;
falseMatrix= zeros(7,7);
targetMatrix= ones(7,7);
checkMatrix= ones(7,7);
if targetMatrix == checkMatrix
%     cam = camStop;
    return
end

Answer 1

[Image Analyst]

If "mask" is the image you want to count black pixels in, you can either do it like this:

numBlackPixels = numel(mask) - nnz(mask)

or like this:

numBlackPixels = sum(~mask(:))

[Jonathan Maness]

So I enetered this in and then ended the program by saying

disp(numBlackPixels)

So that I can see how many black pixels are in the image, but the command window is not showing anything for the amount of pixels in the image.

[Jonathan Maness]

Nevermind, I got it to work, thanks for your help!

[Image Analyst]

For others, he probably did:

fprintf('mask has %d black pixels.\n', numBlackPixels);
[rows, columns, numberOfColorChannels] = size(mask);
fprintf('mask has %d rows and %d columns.\n', rows, columns);

[Jonathan Maness]

The If statement at the end of my original code was messing it up, so all I had to do was get rid of the entire if statement and then add in the line of code that you have me.