Local binary patterns
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transitions) is not. In the computation of the LBP histogram, the
histogram has a separate bin for every uniform pattern, and all
non-uniform patterns are assigned to a single bin. Using uniform
patterns, the length of the feature vector for a single cell reduces
from 256 to 59. The 58 uniform binary patterns correspond to the
integers 0, 1, 2, 3, 4, 6, 7, 8, 12, 14, 15, 16, 24, 28, 30, 31, 32, 48,
56, 60, 62, 63, 64, 96, 112, 120, 124, 126, 127, 128, 129, 131, 135,
143, 159, 191, 192, 193, 195, 199, 207, 223, 224, 225, 227, 231, 239,
240, 241, 243, 247, 248, 249, 251, 252, 253, 254 and 255.
Extensions
β’ Over-Complete Local Binary Patterns (OCLBP):cite-ref-9[9] OCLBP is a variant of
LBP that has been shown to improve the overall performance on face
verification. Unlike LBP, OCLBP adopts overlapping to adjacent blocks.
Formally, the configuration of OCLBP is denoted as S : (a, b, v, h, p,
r): an image is divided into aΓb blocks with vertical overlap of v and
horizontal overlap of h, and then uniform patterns LBP(u2,p,r) are
extracted from all the blocks. Moreover, OCLBP is composed of several
different configurations. For example, in their original paper, the
authors used three configurations: S :
(10,10,12,12,8,1),(14,14,12,12,8,2),(18,18,12,12,8,3). The three
configurations consider three block sizes: 10Γ10, 14Γ14, 18Γ18, and half
overlap rates along the vertical and horizontal directions. These
configurations are concatenated to form a 40877 dimensional feature
vector for an image of size 150x80.
β’ Transition Local Binary Patterns(tLBP):cite-ref-10[10] binary value of transition
coded LBP is composed of neighbor pixel comparisons clockwise direction
for all pixels except the central.
β’ Direction coded Local Binary Patterns(dLBP): the dLBP encodes the
intensity variation along the four basic directions through the central
pixel in two bits.
β’ Multi-block LBP: the image is divided into many blocks, a LBP
histogram is calculated for every block and concatenated as the final
histogram.
β’ Volume Local Binary Pattern(VLBP):cite-ref-11[11] VLBP looks at dynamic texture
as a set of volumes in the (X,Y,T) space where X and Y denote the
spatial coordinates and T denotes the frame index. The neighborhood of a
pixel is thus defined in three dimensional space, and volume textons can
be extracted into histograms.
β’ RGB-LBP: This operator is obtained by computing LBP over all three
channels of the RGB color space independently, and then concatenating
the results together.
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