这是我们的图像处理作业练习。我的代码可以正常工作。我希望能够得到一些关于代码优化的帮助。
function C = convolve_slow(A,B)
(file name is accordingly convolve_slow.m )
This routine performs convolution between an image A and a mask B.
Input: A - a grayscale image (values in [0,255])
B - a grayscale image (values in [0,255]) serves as a mask in the convolution.
Output: C - a grayscale image (values in [0,255]) - the output of the convolution.
C is the same size as A.
Method: Convolve A with mask B using zero padding. Assume the origin of B is at
floor(size(B)/2)+1.
Do NOT use matlab convolution routines (conv,conv2,filter2 etc).
Make the routine as efficient as possible: Restrict usage of for loops which are expensive (use matrix multiplications and matlab routines such as dot etc).
To simplify and reduce ifs, you should pad the image with zeros before starting your convolution loop.
Do not assume the size of A nor B (B might actually be larger than A sometimes).
这是我们的解决方案
function [ C ] = convolve_slow( A,B )
%This routine performs convolution between an image A and a mask B.
% Input: A - a grayscale image (values in [0,255])
% B - a grayscale image (values in [0,255]) serves as a mask in the convolution.
% Output: C - a grayscale image (values in [0,255]) - the output of the convolution.
% C is the same size as A.
%
% Method: Convolve A with mask B using zero padding. Assume the origin of B is at floor(size(B)/2)+1.
% init C to size A with zeros
C = zeros(size(A));
% make b xy-reflection and vector
vectB = reshape(flipdim(flipdim(B,1),2)' ,[] , 1);
% padding A with zeros
paddedA = padarray(A, [floor(size(B,1)/2) floor(size(B,2)/2)]);
% Loop over A matrix:
for i = 1:size(A,1)
for j = 1:size(A,2)
startAi = i;
finishAi = i + size(B,1) - 1;
startAj = j;
finishAj = j + size(B,2) - 1;
vectPaddedA = reshape(paddedA(startAi :finishAi,startAj:finishAj)',1,[]);
C(i,j) = vectPaddedA* vectB;
end
end
end
因为我是新手,对于图像处理和Matlab还不熟悉。你能帮助我优化代码吗?特别是关于矩阵运算方面。是否有可能不使用循环语句?