Storing Data from an IF loop

Hi all

so i run a foor loop to get the number of pixels in a sample of images, I then want to find the the jumps that are larger 400 pixels, and the store the x value where this occurs, any idea?

thank you in advance :)

x=0;

  for x=1:1:56;
    
    x=x+1;  
    
    jump(x)=whitepixels9(x)-whitepixels9(x-1);
    
    if -400>jump>400 ; 
        
        
    end 
  end  

Answer 1

[Adam Danz]

There is no such thing as an 'if loop'. There are while loops and for loops but an 'if' statement is a conditional.

If whitepixels9() can operate on vectors, you do not need to (and should not) use a for-loop.

If you must use a for loop, here are some comments to consider:

 % x=0;                            % Remove.  Unnecessary.
jump = nan(1,56);
for x=1:1:56;     
    
    %x=x+1;                        % Remove.  The for-loop does this automatically
    
    % The line below assumes that the output is a scalar
    jump(x)=whitepixels9(x)-whitepixels9(x-1);
    
   % if -400>jump>400 ;            % Remove.  
   %    
   % end
   
end
keepX = find(jump > 400);

[Lizzy tatarek]

I do this but it shows no jumps larger than 400 even though there definitely are?

[Adam Danz]

I just edited my answer. Try that.

Answer 2

[KALYAN ACHARJYA]

image1=rgb2gray(imread('test.jpg')); % image1 gray image
[rows colm]=size(image1);
fprintf('The number of pixel in the image= %d ',rows*colm);
result1=sort(image1(:,:),'descend');  
max_pixels=result1(1:400);

% Next find the indexes wheere max_pixels any elements equal in image 1

Answer 3

[Lizzy tatarek]

 

 for x=2:1:56
 jump(x)=whitepixels9(x)-whitepixels9(x-1);

    if jump(x)>400
    jump(x)=whitepixels9(x);
    else
    jump(x)=0;
    end
 end 

I ended up doing this which is fit for my use and made it possible to plot it on a graph of the pixel number in each image