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# How to do median filter on an indexed image using MATLAB?

By : 777
Date : January 10 2021, 01:57 PM
hop of those help? From the medfilt2 documentation:
B = medfilt2(A, 'indexed', ...) processes A as an indexed image, padding with 0s if the class of A is uint8, or 1s if the class of A is double.
code :

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## How can I apply a ring-shaped median filter to an image in matlab?

Date : March 29 2020, 07:55 AM
For example, if your "ring" is just defined by:
code :
``````ring= fspecial('gaussian',21,1)
ring = ring>eps & ring<1e-9
``````
``````order=sum(ring(:))/2;
B = ordfilt2(A,order,ring);
``````

## Median filter binary image with 3x3 mask in Matlab

By : user3159310
Date : March 29 2020, 07:55 AM
This might help you The short answer is you can use nlfilter where you can specify what is done on pixel neighbourhoods in your image. Specifically, you would call nlfilter like so:
code :
``````B = nlfilter(A, [m n], fun);
``````
``````out = nlfilter(im, size(mask), @(x) median(x(mask)));
``````
``````N = size(mask,1); %// Size of mask - Assume that # of rows = # of columns
im_col = im2col(im_pad, [N N], 'sliding');

%// Get locations in mask that don't count towards getting median

%// Remove from column neighbourhood matrix
im_col(invalid_rows,:) = [];

%// Determine new median index
val = floor((N*N - sum(invalid_rows))/2) + 1;

%// apply algorithm as normal
sorted_cols = sort(im_col, 1, 'ascend');
med_vector = sorted_cols(val, :);
out = col2im(med_vector, [N N], size(im_pad), 'sliding');
``````

## How to implement median filter with a kernel in MATLAB to smooth an image?

By : user894627
Date : March 29 2020, 07:55 AM
I hope this helps you . I don't know how to implement a median filter with a sliding window (kernel) in MATLAB. I need to know how the implementation looks like so I can try to implement a BSE algorithm (block smart erase), which is very similar to the median filter. I need that to erase some black and white pixels. I know that there's the medfilt2() function but I need to know how it is implemented. , you can implement median filter as below:
code :
``````function [outimg] = medianfilt(img,sz)
[rows,cols] = size(img);    % get size of grayscale image
outimg = zeros(rows,cols);  % output / median filtered image
for x = pad/2 + 1 : cols + pad/2  % loop over columns
for y = pad/2 + 1 : rows + pad/2   % loop over rows
end
end
end
``````
``````if nimg(y,x) == 0 || nimg(y,x) == 255
else
end
``````

## Matlab code of median filter or other filters for image enhancement

By : Suphakit Kaosaeng
Date : March 29 2020, 07:55 AM
hope this fix your issue Matlab has a built-in for image median filtering which is medfilt2d.
If you want to design your own filter and play around, you can use imfilter to apply linear filters (i.e. convolve your image with a discrete kernel) and nlfilter for non linear filters.

## 3D median filter in Matlab

By : rahul gupta
Date : March 29 2020, 07:55 AM
it fixes the issue Would it be acceptable to do the median filtering in separable passes, e.g., first a 5x5 medfilt2 operation in xy and then a 5x1 medfilt along z?