An example of image processing using matlab

function [imgdatadb,mymask]=rgb2whiteblack(ImgFileName,mymask) %  To show some basic image processing (percentage of some colors) %  using matlab. Also shows how to create a mask using mouse. %  Copyright: http://scriptdemo.blogspot.com IsFig=0; IsFinalFig=1; % read image if nargin==0     ImgFileName='8x.JPG'; end if ~exist(ImgFileName,'file')     disp(['image file: ',ImgFileName,' cannot be found!!! return nothing'])     imgdatadb=[];mymask=[];     return end % assume input image is in rgb mode imgrgb=imread(ImgFileName); % Be more accurate or professional, consider operations with rgb channels if ~exist('mymask','var')    %create the mask    mask1=roipoly(imgrgb);    mask2=roipoly(imgrgb);    mask3=roipoly(imgrgb);    mymask=mask1+mask2+mask3;    close; end if IsFig % show rgb channels of the image    figure;    for N=1:4        subplot(2,2,N);        if N~=4           imagesc(imgrgb(:,:,N));        else           imagesc(imgrgb);        end    end end % convert data into gray scale [intensity image] imgdata=rgb2gray(imgrgb); % or maybe consider rgb2bw %convert to double imgdatadb=double(imgdata); % convert dark part to black imgdatadb(imgdatadb<100)=0; % ..      light part to white imgdatadb(imgdatadb>=100)=255; % set mask region to specified value, e.g., 90 imgdatadb(mymask==1)=90; % statistics NumOfMaskP=length(find(mymask==1)); NumOfEffectiveP=length(imgdatadb(:))-NumOfMaskP; PerEffective=NumOfEffectiveP/(NumOfMaskP+NumOfEffectiveP)*100; PerBlack=length(find(imgdatadb==0))/NumOfEffectiveP*100; % show percentage disp(['Percentage of Effective  pixels (%): ',num2str(PerEffective)]) disp(['Percentage of black region (%): ',num2str(PerBlack)]) % show image if IsFinalFig    figure;    title('Origin Gray image');imagesc(imgdata);    figure;    title('Black and White'); imagesc(uint8(imgdatadb)); end

Plot a heart curve in matlab

 

function ShowHeart(Ntype) % a funny script to show different kind of heart curves % Usage: %        ShowHeart() % Copyright: http://scriptdemo.blogspot.com % Ref: http://www.mathematische-basteleien.de/heart.htm %        http://mathworld.wolfram.com/HeartCurve.html if nargin==0 Ntype=1; end np=999;Is3D=0;IsFilled=1; switch Ntype     case {1}        t=0:2*pi/np:2*pi;        xx=(1-sin(t)).*cos(t);        yy=(1-sin(t)).*sin(t);     case {2}        t=-1:2/(np*100):1;        xx=sin(t).*cos(t).*log(abs(t));        yy=sqrt(cos(t)).*abs(t).^0.3;        yy(isnan(xx))=[];        xx(isnan(xx))=[];     case {3}        t=-1:2/(np*100):1;        xx=sin(t).*cos(t).*log(abs(t));        yy=sqrt(abs(t)).*cos(t);        yy(isnan(xx))=[];        xx(isnan(xx))=[];     case {4}        t=0:2*pi/np:2*pi;        r=sin(t).*sqrt(abs(cos(t)))./(sin(t)+7/5)-2*sin(t)+2;        xx=r.*cos(t); yy=r.*sin(t); clear r     case {5}        t=0:60/np:60;        r=0.01*(-t.*t+40*t+1200);        xx=r.*sin(pi*t/180);        yy=r.*cos(pi*t/180); clear r t        xx=[xx fliplr(-xx)]; yy=[yy fliplr(yy)];     case {6}        t=-1:2/(np*100):1;        r=(1-abs(t)).*(1+3*abs(t));        xx=r.*sin(t); yy=r.*cos(t); clear r t     otherwise        disp(['Sorry, you just broke my heart!']);        Is3D=1;        t=0:2*pi/np:2*pi;        r=sin(t).*sqrt(abs(cos(t)))./(sin(t)+7/5)-2*sin(t)+2;        xx=r.*cos(t); yy=r.*sin(t); clear r end if ~Is3D    if ~IsFilled       plot(xx,yy,'color','r');    else       hf=fill(xx,yy,'r');set(hf,'linestyle','none');    end else   hp=plot(xx,yy,'g');set(hp,'linestyle','none');   figurenicer; hold on;   myxlim=xlim;myylim=ylim;   nrp=50;   nxgrid=20;   nygrid=20;   xxn=linspace(myxlim(1),myxlim(2),nxgrid);   yyn=linspace(myylim(1),myylim(2),nygrid);   [xxn,yyn]=meshgrid(xxn,yyn);   tmprand=randn(nrp,2);   tmprand=tmprand/max(abs(tmprand(:)))/2;   xxrand=zeros(nrp,nxgrid*nygrid);   yyrand=xxrand;   np=1;   for Nx=1:nxgrid       for Ny=1:nygrid          xxrand(:,np)=xxn(Ny,Nx)+tmprand(:,1);          yyrand(:,np)=yyn(Ny,Nx)+tmprand(:,2);          np=np+1;       end   end   Ind=inpolygon(xxn(:),yyn(:),xx(:),yy(:));   tmpind=1:length(xxn(:));   [jj,ii]=ind2sub(size(xxn),tmpind(Ind==1));   Ind2=sub2ind(size(xxn),jj(:)+1,ii(:));   Ind=sub2ind(size(xxn),jj(:),ii(:));   xxrand(:,Ind2)=xxrand(:,Ind);   yyrand(:,Ind2)=yyrand(:,Ind);      [xxnew,yynew]=GetRandom(xx(:),yy(:),5);   hp0=plot(xxnew,yynew,'g.');set(hp0,'linestyle','none','markersize',1);   %plot(xxn(:),yyn(:),'.b');   hp=plot(xxrand,yyrand,'.g');set(hp,'linestyle','none','markersize',1); end figurenicer; axis equal; axis tight; function [xxnew,yynew]=GetRandom(xx,yy,nrp)  np=length(xx);  if (np>360)     iii=linspace(1,np,360);     iii=fix(iii);     xx=xx(iii); yy=yy(iii);     np=length(xx);  end  tmprand=randn(nrp,2);  tmprand=tmprand/max(abs(tmprand(:)))*8;  xxnew=zeros(nrp,length(xx));  xx=reshape(xx,1,[]);  yy=reshape(yy,1,[]);  xxdif=diff(xx);xxdif=[xxdif(1) xxdif];  yydif=diff(yy);yydif=[yydif(1) yydif];  for N=2:length(xx)      xxnew(:,N)=0.5*(xx(N-1)+xx(N))+tmprand(:,1)*xxdif(N);      yynew(:,N)=0.5*(yy(N-1)+yy(N))+tmprand(:,2)*yydif(N);  end xxnew(:,1)=xxnew(:,2); yynew(:,1)=yynew(:,2);