Matlab的旋转不变lbp特征提取代码

以下是MATLAB中旋转不变LBP特征提取的代码：

function lbp_feat = rotation_invariant_lbp(img, radius, neighbors)
% img: 输入的图像
% radius: LBP算子半径
% neighbors: LBP算子采样点数
% lbp_feat: LBP特征

if nargin < 3
    neighbors = 8;
end
if nargin < 2
    radius = 1;
end

% 获取图像尺寸
[rows, cols] = size(img);

% 初始化LBP特征图
lbp_feat_map = zeros(rows, cols);

% 计算LBP特征图
for i = 1 : rows
    for j = 1 : cols
        lbp_feat_map(i,j) = get_lbp_pixel(img, i, j, radius, neighbors);
    end
end

% 计算旋转不变LBP特征
lbp_feat = zeros(1, 2^neighbors);
for i = 0 : neighbors-1
    % 将特征图沿着采样点方向旋转
    lbp_feat_map_rotated = imrotate(lbp_feat_map, i*360/neighbors, 'nearest', 'crop');
    
    % 计算LBP直方图
    lbp_hist = histcounts(lbp_feat_map_rotated(:), 0:2^neighbors);
    
    % 更新LBP特征
    lbp_feat = lbp_feat + lbp_hist;
end

% 归一化LBP特征
lbp_feat = lbp_feat / sum(lbp_feat);

end

function lbp_pixel = get_lbp_pixel(img, row, col, radius, neighbors)
% img: 输入的图像
% row, col: 中心像素坐标
% radius: LBP算子半径
% neighbors: LBP算子采样点数
% lbp_pixel: LBP像素值

% 获取图像尺寸
[rows, cols] = size(img);

% 初始化采样点坐标
sample_points = zeros(neighbors, 2);

% 计算采样点坐标
for i = 1 : neighbors
    theta = 2*pi*(i-1)/neighbors;
    sample_points(i,1) = row + radius*cos(theta);
    sample_points(i,2) = col - radius*sin(theta);
end

% 处理采样点坐标越界的情况
sample_points(sample_points(:,1)<1 | sample_points(:,1)>rows | sample_points(:,2)<1 | sample_points(:,2)>cols, :) = [];

% 计算LBP像素值
lbp_pixel = 0;
for i = 1 : size(sample_points, 1)
    if img(round(sample_points(i,1)), round(sample_points(i,2))) >= img(row, col)
        lbp_pixel = lbp_pixel + 2^(i-1);
    end
end

end

使用方法：

% 读取图像
img = imread('lena.png');

% 计算旋转不变LBP特征
lbp_feat = rotation_invariant_lbp(img, 1, 8);