%GETMAPPING returns a structure containing a mapping table for LBP codes.
% MAPPING = GETMAPPING(SAMPLES,MAPPINGTYPE) returns a
% structure containing a mapping table for
% LBP codes in a neighbourhood of SAMPLES sampling
% points. Possible values for MAPPINGTYPE are
% 'u2' for uniform LBP
% 'ri' for rotation-invariant LBP
% 'riu2' for uniform rotation-invariant LBP.
%
% Example:
% I=imread('rice.tif');
% MAPPING=getmapping(16,'riu2');
% LBPHIST=lbp(I,2,16,MAPPING,'hist');
% Now LBPHIST contains a rotation-invariant uniform LBP
% histogram in a (16,2) neighbourhood.
%
function mapping = getmapping(samples,mappingtype)
% Version 0.2
% Authors: Marko Heikkil?, Timo Ahonen and Xiaopeng Hong
% Changelog
% 0.1.1 Changed output to be a structure
% Fixed a bug causing out of memory errors when generating rotation
% invariant mappings with high number of sampling points.
% Lauge Sorensen is acknowledged for spotting this problem.
% Modified by Xiaopeng HONG and Guoying ZHAO
% Changelog
% 0.2
% Solved the compatible issue for the bitshift function in Matlab
% 2012 & higher
matlab_ver = ver('MATLAB');
matlab_ver = str2double(matlab_ver.Version);
if matlab_ver < 8
mapping = getmapping_ver7(samples,mappingtype);
else
mapping = getmapping_ver8(samples,mappingtype);
end
end
function mapping = getmapping_ver7(samples,mappingtype)
disp('For Matlab version 7.x and lower');
table = 0:2^samples-1;
newMax = 0; %number of patterns in the resulting LBP code
index = 0;
if strcmp(mappingtype,'u2') %Uniform 2
newMax = samples*(samples-1) + 3;
for i = 0:2^samples-1
j = bitset(bitshift(i,1,samples),1,bitget(i,samples)); %rotate left
numt = sum(bitget(bitxor(i,j),1:samples)); %number of 1->0 and
%0->1 transitions
%in binary string
%x is equal to the
%number of 1-bits in
%XOR(x,Rotate left(x))
if numt <= 2
table(i+1) = index;
index = index + 1;
else
table(i+1) = newMax - 1;
end
end
end
if strcmp(mappingtype,'ri') %Rotation invariant
tmpMap = zeros(2^samples,1) - 1;
for i = 0:2^samples-1
rm = i;
r = i;
for j = 1:samples-1
r = bitset(bitshift(r,1,samples),1,bitget(r,samples)); %rotate
%left
if r < rm
rm = r;
end
end
if tmpMap(rm+1) < 0
tmpMap(rm+1) = newMax;
newMax = newMax + 1;
end
table(i+1) = tmpMap(rm+1);
end
end
if strcmp(mappingtype,'riu2') %Uniform & Rotation invariant
newMax = samples + 2;
for i = 0:2^samples - 1
j = bitset(bitshift(i,1,samples),1,bitget(i,samples)); %rotate left
numt = sum(bitget(bitxor(i,j),1:samples));
if numt <= 2
table(i+1) = sum(bitget(i,1:samples));
else
table(i+1) = samples+1;
end
end
end
mapping.table=table;
mapping.samples=samples;
mapping.num=newMax;
end
function mapping = getmapping_ver8(samples,mappingtype)
disp('For Matlab version 8.0 and higher');
table = 0:2^samples-1;
newMax = 0; %number of patterns in the resulting LBP code
index = 0;
if strcmp(mappingtype,'u2') %Uniform 2
newMax = samples*(samples-1) + 3;
for i = 0:2^samples-1
i_bin = dec2bin(i,samples);
j_bin = circshift(i_bin',-1)'; %circularly rotate left
numt = sum(i_bin~=j_bin); %number of 1->0 and
%0->1 transitions
%in binary string
%x is equal to the
%number of 1-bits in
%XOR(x,Rotate left(x))
if numt <= 2
table(i+1) = index;
index = index + 1;
else
table(i+1) = newMax - 1;
end
end
end
if strcmp(mappingtype,'ri') %Rotation invariant
tmpMap = zeros(2^samples,1) - 1;
for i = 0:2^samples-1
rm = i;
r_bin = dec2bin(i,samples);
for j = 1:samples-1
r = bin2dec(circshift(r_bin',-1*j)'); %rotate left
if r < rm
rm = r;
end
end
if tmpMap(rm+1) < 0
tmpMap(rm+1) = newMax;
newMax = newMax + 1;
end
table(i+1) = tmpMap(rm+1);
end
end
if strcmp(mappingtype,'riu2') %Uniform & Rotation invariant
newMax = samples + 2;
for i = 0:2^samples - 1
i_bin = dec2bin(i,samples);
j_bin = circshift(i_bin',-1)';
numt = sum(i_bin~=j_bin);
if numt <= 2
table(i+1) = sum(bitget(i,1:samples));
else
table(i+1) = samples+1;
end
end
end
mapping.table=table;
mapping.samples=samples;
mapping.num=newMax;
end
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