Question

as a part of my homework i need to implement this pattern matching.
the goal is to “Detect as many of the 0’s (zeros) as you can in image coins4.tif.”

i was given the NGC function. and i need to use it

this is my main.m file

Image = readImage('coins4.tif');
Pattern = readImage('zero.tif');
showImage(Image);
showImage(Pattern);
message = sprintf('Pattern matching Normalized Correlation');
PatternMatching(Image , Pattern);
uiwait(msgbox(message,'Done', 'help'));
close all

this is my PatternMatching function.

function [ output_args ] = PatternMatching( Image , Pattern )
% Pattern matching – Normalized Correlation
% Detect as many of the 0's (zeros) as you can in image coins4.tif.
% Use the 0 of the 10 coin as pattern.
% Use NGC_pm and find good threshold. Display original image with? detected regions marked using drawRect.

% NGCpm(im,pattern);
% drawRect(rectCoors,color);
% rectCoors = [r0,c0,rsize,csize]  - r0,c0 = top-left corner of rect.
%             rsize = number of rows, csize = number of cols
%
% color = an integer >=1 representing a color in the color wheel
%                   (curerntly cycles through 8 different colors

showImage(Image);
hold on
res = NGCpm(Image, Pattern);

 for i = 1:size(res,1)
     for j = 1:size(res,2)
         if res(i,j) > 0.9999
             drawRect([i j size(Pattern,1) size(Pattern,2)], 5)
         end
     end
 end

end

this is the Given NGCpm.m file

function res=NGC_PM(im,pattern)
[n m]=size(pattern);
[im_row,im_col]=size(im);
if ~(var(pattern(:))==0)
     res = normxcorr2(pattern, im);
     res=res(n:im_row,m:im_col);   
else
    res=zeros(size(im)-size(pattern)+1);
end;
 res = 1-abs(res);  % res = abs(res);

this is the pattern i’m trying to find and the results, i’m getting

i’m trying to find as many “Zeros” as possiable using the zero pattern of the coin 10.

i’m tryingto understand if there is something wrong with my algorithm in the PatternMatching function. since the NGCpm function is already given to me, all i need to do is just loop of the best threshold ,correct?

or do i need to blur the image or the pattern?

Answer 1

this is the fixed version of this function.

function [ output_args ] = patternMatching( Image , Pattern )
% Pattern matching – Normalized Correlation
% Detect as many of the 0's (zeros) as you can in image coins4.tif.
% Use the 0 of the 10 coin as pattern.
% Use NGC_pm and find good threshold. Display original image with? detected regions marked using drawRect.

% NGCpm(im,pattern);
% drawRect(rectCoors,color);
% rectCoors = [r0,c0,rsize,csize]  - r0,c0 = top-left corner of rect.
%             rsize = number of rows, csize = number of cols
%
% color = an integer >=1 representing a color in the color wheel
%                   (curerntly cycles through 8 different colors

showImage(Image);
hold on
res = 1-NGCpm(Image, Pattern);
normalized_corellation = uint8(255*res/max(max(res)));
res_thresh = thresholdImage(normalized_corellation,100);
 for i = 1:size(res_thresh,1)
     for j = 1:size(res_thresh,2)
         if res_thresh(i,j) > 0
             drawRect([i j size(Pattern,1) size(Pattern,2)], 5)
         end
     end
 end

end