Shrinking image by averaging
显示 更早的评论
I want to create a function: shrinkbyaveraging(imagematrix) that returns an image that is half as large in both height and width. Each pixel in the returned image should be the average of 4 pixels from the input image. Shrinkbyaveraging only needs to work for images having an even number of rows/columns. However, I do not want to use imresize.
function shrink = shrinkbyaveraging(imagematrix) [row,colm] = size(imagematrix); x = row/2; y = colm/2;
but im not sure what the question is asking since i cannot use imresize. :/
4 个评论
KALYAN ACHARJYA
2018-10-17
What you have done so far, please share?
Image Analyst
2018-10-17
If you do not want to use imresize(), then I guess you do not want to use interp2() either, and do not want to use anyone else's function or code. So, how can we help? Point you to Wikipedia's page on bilinear interpolation??? And to this page on how to format your code?
Rik
2020-11-20
编辑：John Kelly
2021-1-15
Rik
2020-11-20
编辑：John Kelly
2021-1-15
Also some deleted comments :
OP responding to Kalyan:
function shrink = shrinkbyaveraging(imagematrix) [row,colm] = size(imagematrix); x = row/2; y = colm/2;
but im not sure what the question is asking since i cannot use imresize. :/
OP responding to Image Analyst:
I am taking a first year introductory computing science course and I dont think it is that hard. But, I am stuck on it.
回答（2 个）
Michael Hawks
2018-10-17
Try this:
Nrow = 12; Ncol = 15;
input = rand(Nrow,Ncol);
shifts = [0 0; 0 1; 1 0; 0 -1];
A = zeros(Nrow,Ncol,4);
for ii = 1:4;
out(:,:,ii) = circshift( input, shifts(ii,:) );
end
out = sum( out, 3);
out = out(2:2:end,2:2:end);
In the for loop, we're building up an mxnx4 array of shifted copies of the input array. Then finding the mean over the neighborhood is as easy as averaging along dimension 3. Then the last line downsamples the array to the size you want.
Sean de Wolski
2021-1-15
This works
img = repmat(1:6,4,1)
shrink = @(x)reshape(sum(reshape(sum(reshape(x,2,1,[])),size(x,1)/2,2,[]),2)./4,size(x,1)/2,[])
shrink(img)
类别
在 帮助中心 和 File Exchange 中查找有关 Matrix Indexing 的更多信息
2021-1-15
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!
Translated by 
