图像白平衡算法

function imgout = Gray_Axis_Alignment(imgin,ratio) %功能：改程序实现了基于灰度轴调整的彩色图像的自动白平衡方法 %参考文献：基于灰轴调整的彩色图像自动白平衡 天津大学 2010 if nargin == 1 ratio = 0.005; end imgin = double(imgin); [sizex,sizey,sizez] = size(imgin); if sizez~=3 error('输入图像出现了错误'); end %取出三通道 Ir = imgin(:,:,1);Ig = imgin(:,:,2);Ib = imgin(:,:,3); imgout = zeros(sizex,sizey,sizez); %获取亮度值 Limg = max(Ir,Ig); Limg = max(Limg,Ib); pixelvalue = reshape(Limg,1,sizex*sizey); [~,index] = sort(pixelvalue,'descend'); num = ceil(sizex*sizey*ratio); points = zeros(num,2); for i=1:num points(i,1) = rem(index(i),sizex); if points(i,1) == 0 points(i,1) = sizex; end points(i,2) = ceil(index(i)/sizex); end %计算最大值的平均值 Re = 0; Ge = 0; Be = 0; for i=1:num Re = Re + Ir(points(i,1),points(i,2)); Ge = Ge + Ig(points(i,1),points(i,2)); Be = Be + Ib(points(i,1),points(i,2)); end Re = Re/num; Ge = Ge/num;Be = Be/num; OE = [Re,Ge,Be]; clear points num index %实现坐标轴的旋转 OP = [255 255 255]; OZ = cross(OE,OP);%向量的叉乘 %第一步旋转 Rz = OZ(1);Gz = OZ(2); Bz = OZ(3); sinphi = Gz/sqrt(Gz^2+Bz^2);cosphi = Bz/sqrt(Gz^2+Bz^2); Mr = [1 0 0;0,cosphi,sinphi;0 -sinphi, cosphi]; clear sinphi cosphi %第二步旋转 cosphi = sqrt(Gz^2+Bz^2)/norm(OZ,2); sinphi = -Rz/norm(OZ,2); Mg = [cosphi 0 -sinphi; 0 1 0; sinphi, 0 cosphi]; clear sinphi cosphi %第三步旋转 cosphi = dot(OE,OP)/(norm(OE,2)*norm(OP,2)); sinphi = norm(OZ,2)/(norm(OE,2)*norm(OP,2)); Mb = [cosphi sinphi 0; -sinphi cosphi 0; 0 0 1]; %得到最后的矩阵 M = Mr*Mg*Mb*Mg'*Mr'; %计算beta beta = norm(OP,2)/norm(OE,2); %进行映射 for i = 1:sizex for j = 1:sizey temp = [Ir(i,j),Ig(i,j),Ib(i,j)]*M; imgout(i,j,1) = beta*temp(1); imgout(i,j,2) = beta*temp(2); imgout(i,j,3) = beta*temp(3); end end imgout = ceil(imgout); imgout = uint8(imgout); end