Counting the number of medium-sized buttons on the image using Matlab

Question

I tried to select borders and then calculate the area. Вut I'm having some difficulty with this. Here's my original image.

After after some processing of the original image I obtained this image:

Here's my code:

    clear;
    I=imread('C:\Users\Sashka\Desktop\calculator.jpg');
    i=rgb2gray(I);
    background = imopen(i,strel('disk',20));
    im=histeq(background, 64);
    uns=fspecial('unsharp') ;  
    uns1=imfilter(im, uns);
    bw = im2bw(uns1,0.3); 
    bw2=bwmorph(bw, 'close', Inf);
    bw3=bwmorph(bw2, 'majority', Inf);
    bw4=bwmorph(bw3, 'erode', 18);
    c=[30 30 440 440];
    r=[480 680 680 480];
    bw5=bwselect(bw4,c,r,4);
    I2=imcrop(bw5, [30 25 1300 1090]);

Can You please help me to count the number of medium-sized buttons?

Answer 1

Just use regionprops and define a threshold of the maximum or minimum area of the desired buttons, example:

your code plus...

original = imcrop(i, [30 25 1300 1090]);

L_Measurements = regionprops(~I2, original, 'all');

threshold = 40000;
Areaofbuttons = cell2mat({L_Measurements.Area}');
numberOfButtons = sum( Areaofbuttons > threshold)

which for example gives,

numberOfButtons =

     9