getmapping.m
%?GETMAPPING?returns?a?structure?containing?a?mapping?table?for?LBP?codes.
%??MAPPING?=?GETMAPPING（SAMPLESMAPPINGTYPE）?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（I216MAPPING‘hist‘）;
%??Now?LBPHIST?contains?a?rotation-invariant?uniform?LBP
%??histogram?in?a?（162）?neighbourhood.
%


function?mapping?=?getmapping（samplesmappingtype）
%?Version?0.1.1
%?Authors:?Marko?Heikkil?and?Timo?Ahonen


%?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.


?


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（i1samples）1bitget（isamples））;?%rotate?left
????numt?=?sum（bitget（bitxor（ij）1:samples））;?%number?of?1->0?and
???????????????????????????????????????????????%0->1?transitions
???????????????????????????????????????????????%in?binary?string
???????????????????????????????????????????????%x?is?equal?to?the
???????????????????????????????????????????????%number?of?1-bits?in
???????????????????????????????????????????????%XOR（xRotate?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^samples1）?-?1;
??for?i?=?0:2^samples-1
????rm?=?i;
????r??=?i;
????for?j?=?1:samples-1
??????r?=?bitset（bitshift（r1samples）1bitget（rsamples））;?%rotate
?????????????????????????????????????????????????????????????%left
??????if?r?????????rm?=?r;
??????end
????end
????if?tmpMap（rm+1）???????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（i1samples）1bitget（isamples））;?%rotate?left
????numt?=?sum（bitget（bitxor（ij）1:samples））;
????if?numt?<=?2
??????table（i+1）?=?sum（bitget（i1:samples））;
????else
??????table（i+1）?=?samples+1;
????end
??end
end


mapping.table=table;
mapping.samples=samples;
mapping.num=newMax;