Image detect and convert white image

I want to convert like this,,,, detect image and convert in to whole white, because i have to count white pixels

Answer 1

[Walter Roberson]

filename = 'https://www.mathworks.com/matlabcentral/answers/uploaded_files/1015940/image.png';
img = imread(filename);

negmask = all(img > 240, 3);
mask = ~bwareafilt(negmask, 1);
imshow(mask)

area = nnz(mask)

area = 173456

[Walter Roberson]

The 240 that I chose was arbitrary. When I filtered for any component < 240, a small number of small dots were left near the lower right of the object. The bwareafilt is used to select just the largest area, discarding the small dots.

Answer 2

[KSSV]

I = imread('https://in.mathworks.com/matlabcentral/answers/uploaded_files/1015935/test.png') ;
I1 = rgb2gray(I) ; 
I2 = ~imbinarize(I1) ; 
imshow(I2)

Answer 3

[Matt J]

A=imread('https://www.mathworks.com/matlabcentral/answers/uploaded_files/1015940/image.png');

imshow(any(250-A,3))