DCT系数直图问题

unction B=image_hist(N,bins);
%Please input a square matrix that has multiple of 8 dimensions
%bins should range over at least -20:20
%this takes a histogram of the DCT coefficeient values
[x dnk]=size(N);
x1=x/8;
histogram=zeros(size(bins));
tiled=zeros(8,8,x1,x1);
%break up the matrix into 8x8 tiles and take histogram of DCT
for i=1:x1
for j=1:x1
DCT1=round(dct2(N(8*i-7:i*8,8*j-7:j*8)));
temp=hist(reshape(DCT1, 1,[]), bins);
histogram=histogram+temp;
end
end
B=histogram;
哪位大神可以给解释一下啊 妹子谢过了