自己编写了一个matlab的小程序，用来计算球形纳米粒子的直径，希望对大家有用。这个程序非常简单，只要设置5个参数：前两个是输入和输出文件的路径和名称；第三个是一个数据的门槛，适当的数值可以把纳米粒子和背景区分开；第四个是TEM照片中标尺的大小，单位nm；第五个是估计图中有多少个纳米粒子。详细程序:

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% This programme can select and calculate the size of nanoparticles in TEM picture.
% How to use:
% 1. Input parameters in 'Parameter Setting Part' according to the instructions
% 2. Run program
% 3. Select start and end of the ruler, click two times at different place
% 4. After a flash, click the center of nanoparticles
% 5. The Diameter of nanoparticles is in outfile
% Note: nanoparticles are regarded as a spherical ball
% Built by Xiaochun Zhou, 05-22-2009
% Enjoy it! Any questions? Ask zxczxc0417@163.com.
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

clear;clc;
%------------ Parameter Setting Part -----------------%
infile='E:Documentdata115094-5.jpg'; % TEM figure
outfile='E:Documentdata115094-5.txt'; % Output file of Diameter

thresh = 120; % for figure
dx = 100; % nm, size of the ruler
n_p = 5; % how many particles in your figure
%------------ Parameter Setting Part -----------------%

[x,map] = imread(infile);
[heigth width kjk] = size( x );
x = x(:,:,1);
x = double(x);

for i = 1:heigth
    for j = 1:width       
        if x(i,j) > thresh
            x(i,j) = 0;
        else
            x(i,j) = 100;
        end
       
    end
end

msgbox('select the start and end point ruler in your map!!!!!!!!!!!!');
pause(3);
imshow(x);

[xa,yb] = ginput(2);
dxdy = ( dx/abs( xa(1) - xa(2) ) ) * ( dx/abs( xa(1) - xa(2) ) );

% msgbox(['dxdy = ' num2str(dxdy)]);  
close

imshow(x);

for i = 1:n_p % NP number
    [xa,yb] = ginput (1);
   
    xa = round(xa);
    yb = round(yb);
    area(i) = 0;
   
    for j = 0:1000  
        if x(yb,xa +j) < thresh/2
            break
        end
       
        for yi = 0:1000
            if x(yb + yi,xa +j) < thresh/2
                break
            else
                area(i) = area(i) + 1;
            end
        end
       
        for yi = 1:1000
           
            if x(yb - yi,xa +j) < thresh/2
                break
            else
                area(i) = area(i) + 1;
            end
        end     
       
    end
   
    for j = 1:1000  
        if x(yb,xa -j) < thresh/2
            break
        end
       
        for yi = 0:1000
            if x(yb + yi,xa - j) < thresh/2
                break
            else
                area(i) = area(i) + 1;
            end
        end
       
        for yi = 1:1000
            if x(yb - yi,xa - j) < thresh/2
                break
            else
                area(i) = area(i) + 1;
            end
        end  
       
    end  
   
end
close

for i = 1:n_p % NP number
    area(i) = area(i) * dxdy;
    diameter1(i) = 2*sqrt( area(i)/3.14159 );
end
diameter1 = diameter1';
dlmwrite(outfile,diameter1);