LBP image detection

Hi all , i am new in matlab, i got this function to calculate lbp value i think, but i don't know what to do next, how to compare with other saved images, should i save with the database saved images the value of it's lbp then i compare with the new image, or should i re-calculate the lbp value again for all saved images. Note: the value returned as uint8 matrix i think. any help please in this

    function result = lbp(varargin) 

      % Check number of input arguments.
      error(nargchk(1,5,nargin));

      image=varargin{1};
      d_image=double(image);

      if nargin==1
          spoints=[-1 -1; -1 0; -1 1; 0 -1; -0 1; 1 -1; 1 0; 1 1];
          neighbors=8;
          mapping=0;
          mode='h';
      end

      if (nargin == 2) && (length(varargin{2}) == 1)
          error('Input arguments');
      end

      if (nargin > 2) && (length(varargin{2}) == 1)
          radius=varargin{2};
          neighbors=varargin{3};

          spoints=zeros(neighbors,2);

          % Angle step.
          a = 2*pi/neighbors;

          for i = 1:neighbors
              spoints(i,1) = -radius*sin((i-1)*a);
              spoints(i,2) = radius*cos((i-1)*a);
          end

          if(nargin >= 4)
              mapping=varargin{4};
              if(isstruct(mapping) && mapping.samples ~= neighbors)
                  error('Incompatible mapping');
              end
          else
              mapping=0;
          end

          if(nargin >= 5)
              mode=varargin{5};
          else
              mode='h';
          end
      end

      if (nargin > 1) && (length(varargin{2}) > 1)
          spoints=varargin{2};
          neighbors=size(spoints,1);

          if(nargin >= 3)
              mapping=varargin{3};
              if(isstruct(mapping) && mapping.samples ~= neighbors)
                  error('Incompatible mapping');
              end
          else
              mapping=0;
          end

          if(nargin >= 4)
              mode=varargin{4};
          else
              mode='h';
          end   
      end

      % Determine the dimensions of the input image.
      [ysize xsize] = size(image);

      miny=min(spoints(:,1));
      maxy=max(spoints(:,1));
      minx=min(spoints(:,2));
      maxx=max(spoints(:,2));

      % Block size, each LBP code is computed within a block of size bsizey*bsizex
      bsizey=ceil(max(maxy,0))-floor(min(miny,0))+1;
      bsizex=ceil(max(maxx,0))-floor(min(minx,0))+1;

      % Coordinates of origin (0,0) in the block
      origy=1-floor(min(miny,0));
      origx=1-floor(min(minx,0));

      % Minimum allowed size for the input image depends
      % on the radius of the used LBP operator.
      if(xsize < bsizex || ysize < bsizey)
        error('Too small input image. Should be at least (2*radius+1) x (2*radius+1)');
      end

      % Calculate dx and dy;
      dx = xsize - bsizex;
      dy = ysize - bsizey;

      % Fill the center pixel matrix C.
      C = image(origy:origy+dy,origx:origx+dx);
      d_C = double(C);

      bins = 2^neighbors;

      % Initialize the result matrix with zeros.
      result=zeros(dy+1,dx+1);

      %Compute the LBP code image

      for i = 1:neighbors
        y = spoints(i,1)+origy;
        x = spoints(i,2)+origx;
        % Calculate floors, ceils and rounds for the x and y.
        fy = floor(y); cy = ceil(y); ry = round(y);
        fx = floor(x); cx = ceil(x); rx = round(x);
        % Check if interpolation is needed.
        if (abs(x - rx) < 1e-6) && (abs(y - ry) < 1e-6)
          % Interpolation is not needed, use original datatypes
          N = image(ry:ry+dy,rx:rx+dx);
          D = N >= C; 
        else
          % Interpolation needed, use double type images 
          ty = y - fy;
          tx = x - fx;

          % Calculate the interpolation weights.
          w1 = (1 - tx) * (1 - ty);
          w2 =      tx  * (1 - ty);
          w3 = (1 - tx) *      ty ;
          w4 =      tx  *      ty ;
          % Compute interpolated pixel values
          N = w1*d_image(fy:fy+dy,fx:fx+dx) + w2*d_image(fy:fy+dy,cx:cx+dx) + ...
              w3*d_image(cy:cy+dy,fx:fx+dx) + w4*d_image(cy:cy+dy,cx:cx+dx);
          D = N >= d_C; 
        end  
        % Update the result matrix.
        v = 2^(i-1);
        result = result + v*D;
      end

      %Apply mapping if it is defined
      if isstruct(mapping)
          bins = mapping.num;
          for i = 1:size(result,1)
              for j = 1:size(result,2)
                  result(i,j) = mapping.table(result(i,j)+1);
              end
          end
      end

      if (strcmp(mode,'h') || strcmp(mode,'hist') || strcmp(mode,'nh'))
          % Return with LBP histogram if mode equals 'hist'.
          result=hist(result(:),0:(bins-1));
          if (strcmp(mode,'nh'))
              result=result/sum(result);
          end
      else
          %Otherwise return a matrix of unsigned integers
          if ((bins-1)<=intmax('uint8'))
              result=uint8(result);
          elseif ((bins-1)<=intmax('uint16'))
              result=uint16(result);
          else
              result=uint32(result);
          end
      end

      end

Answer 1

[meng wang]

I'm doing the circular LBP feature,but i have some questions,The result is always white,here's my code,please help me,thanks:

clear;

% 声明默认neighbors为8

I = imread('lena.png');

[rows,cols] = size(I);

neighbors = 8;

radius = 3;

Ibpcode = 0;

CircleLBP = zeros(size(I), 'uint8');

for i = radius+1 : rows-radius

for j = radius+1 : cols-radius

%获得中心像素点的灰度值

centerPixel = I(i, j);

for k = 1 : neighbors

%根据公式计算第k个采样点的坐标

x = i + radius * cos(2.*pi.*k./neighbors);

y = j - radius * sin(2.*pi.*k./neighbors);

%根据取整结果进行双线性插值，得到第k个采样点的灰度值

%1 分别对x，y进行上下取整

x1 = floor(x); %向下取整

x2 = ceil(x); %向上取整

y1 = floor(y); %向下取整

y2 = ceil(y); %向上取整

%2 将坐标映射到0-1之间

tx = x - x1;

ty = y - y1;

%根据0-1之间的x,y的权重计算公式计算权重

w1 = (1 - tx)*(1 - ty);

w2 = tx*(1-ty);

w3 = (1-tx)*ty;

w4 = tx*ty;

%3.根据双线性插值公式计算第k个采样点的灰度值

neighbor = I(x1,y1)*w1 + I(x1,y2)*w2 + I(x2,y1)*w3 + I(x2,y2)*w4;

if(neighbor > centerPixel)

Ibpcode = 2^(neighbors - k -1) + Ibpcode;

end

end

CircleLBP(i,j) = Ibpcode;

end

end

imshow(CircleLBP);

clear;