简易英文ocr程序

% simple ocr code

% only for captital English letters in the same font and fontsize

% other letters can be easily included

% inclination of letters is allowed

% Picture rotated beforehand so that text lines are horizontally oriented

% written by Xiaozhou 12/15/2010

fontname='Times New Roman';

fontsize=10.5;

letters='ABCDEFGHIJKLMNOPQRSTUVWXYZ';

nlt=length(letters);

hltim=round(fontsize*1.5);

wltim=hltim;

filename=[fontname  num2str(nlt) '_' num2str(fontsize) '.mat'];

islibsaved=0; % 0 -  need to create letter image file when use first time; 1 - letter image file exists

if islibsaved==0

    ltimage=lt2im(fontname,fontsize,letters);  % get the image of each letter

    save(filename,'ltimage');

else

    load(filename);

end

picname='test.jpg';

imobj=imread(picname);

imbw=1-im2bw(imobj,0.8);    % convert to black and white pic, then invert color

noise=0.01;  % noise in the pic

iread=1;  % number of letter read

lincl=5;  % left inclination

rincl=5; % right inclination

anginc=5; % angle increment for testing

angs=-rincl:anginc:lincl;

[h,w]=size(imbw);

startrow=1;

% find the first row of pixels containing text

while(sum(imbw(startrow,:))<noise)

 startrow=startrow+1;

end

while(startrow<=h)

 endrow=startrow;

% find the last row of pixels for the txt line

 while(endrow<=h && sum(imbw(endrow,:))>noise)

  endrow=endrow+1;

 end

 imbw1=imbw(startrow:endrow-1,:); % image of the txt line

 startcol=1;

% find the first col of pixels containing text

 while(startcol<=w && sum(imbw1(:,startcol))<noise)

  startcol=startcol+1;

 end

 while(startcol<=w)

  endcol=startcol;

% find the last col of pixels for the letter

  while(endcol<=w && sum(imbw1(:,endcol))>noise)

   endcol=endcol+1;

  end

  imbw2=imbw1(:,startcol:endcol-1); % image of the letter

  imbw3=trimim(imbw2,1); % trim white margin

  [h1,w1]=size(imbw3);

  corrim1=0; % highest correlation factor between tested image and standard letter image

  indlt=1; % index of letter best fit

  anglt=0; % inclination angle best fit

  for k=1:nlt

   imlt=squeeze(1-ltimage(k,:,:));

   for ang=angs

    imlt1=imrotate(imlt,ang); % rotate the standard letter image

    imlt2=trimim(imlt1,1);

    [h2,w2]=size(imlt2);

    tmp1=zeros(hltim,wltim); % create matrix of the same size to contain each image

    tmp2=tmp1;

    tmp1(1:h1,1:w1)=imbw3;

    tmp2(1:h2,1:w2)=imlt2;

    corrim=corr2(tmp1,tmp2);

    if corrim>corrim1

     corrim1=corrim;

     indlt=k;

     anglt=ang;

    end

   end  

        end

  textocr(iread)=letters(indlt);

  iread=iread+1;

% go to the next letter

  startcol=endcol;

  while(startcol<=w && sum(imbw1(:,startcol))<noise)

   startcol=startcol+1;

  end

    end

% go to the next row

 startrow=endrow;

 while(startrow<=h && sum(imbw(startrow,:))<noise)

  startrow=startrow+1;

 end

end

% lt2im.m

% get image data of letters

function ltimage=lt2im(fontname,fontsize,letters)

s=figure;

nlt=length(letters);

h=round(fontsize*1.8);

w=h;

ltimage=ones(nlt,h,w);

for i=1:nlt

    axis off

    h=text(0.5,0.5,letters(i));

    set(h,'FontName',fontname,'Fontsize',fontsize);

    filename=[ num2str(i) '.tif'];

    print(s,'-dtiff','-r0',filename);

    A=imread(filename);

 delete(filename);

    B=im2bw(A);

    B1=trimim(B,0);

%    B2=imresize(B1,[size(B1,1),round(size(B1,2)*1.1)]);

    ltimage(i,1:size(B1,1),1:size(B1,2))=B1;

    clf;

end

close all

% trim white margin

function im1=trimim(im0,fcolor)

[i1,j1]=ind2sub(size(im0),find(im0==fcolor));

imax=max(i1);

imin=min(i1);

jmax=max(j1);

jmin=min(j1);

im1=im0(imin:imax,jmin:jmax);