How to get black pixels and display them in static text

I have an gray scale image and i want to know the total number of pixels, the number of black pixels, and display them in static text GUI. But i can't get the results to show in the static text.

a = handles.grey;
b = handles.imgData;
B = img2double(b);
A = im2double(a);

% black pixels
c = sum(A(:) == 0);

textLabel2 = sprintf(c);
set(handles.areaporos, 'String', textLabel2);

% total pixels
numPixels = numel(B);

textLabel = sprintf(numPixels);
set(handles.areatotal, 'String', textLabel);

Can someone help me figure out what I'm doing wrong? Thank you!

Answer 1

[Image Analyst]

Use a format specifier string in sprintf():

textLabel2 = sprintf('# Black pixels = %d', c);
textLabel = sprintf('Total # of pixels = %d', numPixels);

[sofia cirne]

thank you!

[Image Analyst]

If that fixed the problem, you can "Accept this answer", otherwise you can wait for other solutions.

[sofia cirne]

Actually, it didnt fix the problem. the black pixels counting is wrong. Ive done it with a completly black image and the number of black pixcels doesnt match with the total image pixels. Ive tryied the same with a white image. Can you help me please?

[sofia cirne]

[Walter Roberson]

I suspect that your handles.imgData is RGB that happens to look black and white, in which case it would have three times as many pixels as there would be in the binary image.

[sofia cirne]

That was it. thank you! its was now!

[Image Analyst]

Use this code to make sure the image is gray scale, if you need to make sure it is:

grayImage = imread(fullFileName);
% Get the dimensions of the image.  
% numberOfColorChannels should be = 1 for a gray scale image, and 3 for an RGB color image.
[rows, columns, numberOfColorChannels] = size(grayImage);
if numberOfColorChannels > 1
  % It's not really gray scale like we expected - it's color.
  % Use weighted sum of ALL channels to create a gray scale image.
  grayImage = rgb2gray(grayImage); 
  % ALTERNATE METHOD: Convert it to gray scale by taking only the green channel,
  % which in a typical snapshot will be the least noisy channel.
  % grayImage = grayImage(:, :, 2); % Take green channel.
end