how i can do sub-sampling for an image with factor 4
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Youssef Khmou
2013-2-26
编辑：Youssef Khmou
2013-2-26
hi ,
you can use the function " downsample" twice ,
example :
I=imread('circuit.tif');
J=downsample(I,4);
J=downsample(J',4)';
whos I J
imshow(J)
figure, imshow(I)
Size(I)= 4² * Size(J) .
2 个评论
Wayne King
2013-2-26
编辑：Wayne King
2013-2-26
keep in mind that downsample() in the Signal Processing Toolbox only downsamples the matrix along the row dimension.
Youssef Khmou
2013-2-26
yes Wayne, thanks for reminding , i edited the code .
更多回答（1 个）
Wayne King
2013-2-26
Do you want to downsample along the row dimension, along the column dimension, or both?
X = randn(24,24);
% Along row only
Im = X(1:4:end,:);
% Along column dim only
Im = X(:,1:4:end);
% Along both
Im = X(1:4:end,1:4:end);
Keep in mind that the above gives only one "phase" of the downsampling. When downsampling by M, there are M such phases. To see an illustration of this for a 1-D signal, see
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2013-2-26
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