%**************************************************************************
% 图像检索——提取颜色特征
%HSV空间颜色直方图(将RGB空间转化为HSV空间并进行非等间隔量化，
%将三个颜色分量表示成一维矢量，再计算其直方图作为颜色特征
%function : Hist = ColorHistogram(Image)
%Image : 输入图像数据
%Hist : 返回颜色直方图特征向量256维
%**************************************************************************
function Hist = ColorHistogram(Image)
% Image = imread('E:\\2\\5.jpg');
[M,N,O] = size(Image);
[h,s,v] = rgb2hsv(Image);
H = h; S = s; V = v;
h = h*360;
%*************************************************
% 修改
% for i = 1:M
% for j=1:N
% if v(i,j)<0.15
% H(i,j) = 0;
% S(i,j) = 0;
% V(i,j) = 0;
% end
% if s(i,j)<0.1&v>0.8
% H(i,j) = 0;
% S(i,j) = 0;
% V(i,j) = 1;
% end
% end
% end
%*************************************************
%将hsv空间非等间隔量化：
% h量化成16级；
% s量化成4级；
% v量化成4级；
for i = 1:M
for j = 1:N
if h(i,j)<=15||h(i,j)>345
H(i,j) = 0;
end
if h(i,j)<=25&&h(i,j)>15
H(i,j) = 1;
end
if h(i,j)<=45&&h(i,j)>25
H(i,j) = 2;
end
if h(i,j)<=55&&h(i,j)>45
H(i,j) = 3;
end
if h(i,j)<=80&&h(i,j)>55
H(i,j) = 4;
end
if h(i,j)<=108&&h(i,j)>80
H(i,j) = 5;
end
if h(i,j)<=140&&h(i,j)>108
H(i,j) = 6;
end
if h(i,j)<=165&&h(i,j)>140
H(i,j) = 7;
end
if h(i,j)<=190&&h(i,j)>165
H(i,j) = 8;
end
if h(i,j)<=220&&h(i,j)>190
H(i,j) = 9;
end
if h(i,j)<=255&&h(i,j)>220
H(i,j) = 10;
end
if h(i,j)<=275&&h(i,j)>255
H(i,j) = 11;
end
if h(i,j)<=290&&h(i,j)>275
H(i,j) = 12;
end
if h(i,j)<=316&&h(i,j)>290
H(i,j) = 13;
end
if h(i,j)<=330&&h(i,j)>316
H(i,j) = 14;
end
if h(i,j)<=345&&h(i,j)>330
H(i,j) = 15;
end
end
end
for i = 1:M
for j = 1:N
if s(i,j)<=0.15&&s(i,j)>0
S(i,j) = 0;
end
if s(i,j)<=0.4&&s(i,j)>0.15
S(i,j) = 1;
end
if s(i,j)<=0.75&&s(i,j)>0.4
S(i,j) = 2;
end
if s(i,j)<=1&&s(i,j)>0.75
S(i,j) = 3;
end
end
end
for i = 1:M
for j = 1:N
if v(i,j)<=0.15&&v(i,j)>0
V(i,j) = 0;
end
if v(i,j)<=0.4&&v(i,j)>0.15
V(i,j) = 1;
end
if v(i,j)<=0.75&&v(i,j)>0.4
V(i,j) = 2;
end
if v(i,j)<=1&&v(i,j)>0.75
V(i,j) = 3;
end
end
end
%将三个颜色分量合成为一维特征向量：L = H*Qs*Qv+S*Qv+v；Qs,Qv分别是S和V的量化级数, L取值范围[0,255]
%取Qs = 4; Qv = 4
for i = 1:M
for j = 1:N
L(i,j) = H(i,j)*16+S(i,j)*4+V(i,j);
end
end
%计算L的直方图
for i = 0:255
Hist(i+1) = size(find(L==i),1);
end
Hist = Hist/sum(Hist);
%*********************************************************
%修改使用颜色累加直方图：
% 可以体现两种颜色在颜色轴上的距离和相似性之间的关系
%实验效果不好
%*********************************************************
% HH(1) = Hist(1);
% for i =1:255
% HH(i+1) = HH(i)+Hist(i+1);
% end
% Hist = HH;
%*********************************************************
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