Median filter,block averaging

I have applied Median filter and block averaging on SAR image of tif format. The output image has black lines which are not part of input image. Kindly improve my code to remove these lines.

start_path='E:\practise';
topLevelFolder = start_path;
if topLevelFolder == 0
return;
end
filePattern_1 = sprintf('%s/**/HH/', topLevelFolder);
filePattern = sprintf('%s/*.tif', filePattern_1);

    allFileInfo = dir(filePattern);
    isFolder = [allFileInfo.isdir];
    allFileInfo(isFolder) = [];
    listOfFolderNames = unique({allFileInfo.folder});
numberOfFolders = length(listOfFolderNames);
fprintf('The total number of folders to look in is %d.\n', numberOfFolders);
totalNumberOfFiles = length(allFileInfo);
if totalNumberOfFiles >= 1
for k = 1 : totalNumberOfFiles
% Go through all those files.
thisFolder = allFileInfo(k).folder;
thisBaseFileName = allFileInfo(k).name;
fullFileName = fullfile(thisFolder, thisBaseFileName);
% fprintf('     Processing file %d of %d : "%s".\n', k, totalNumberOfFiles, fullFileName);

% To get images and their georeferencing
      [A,R]=geotiffread(fullFileName);
      
      Y= db2pow(A );
    
      
% %     To apply median filter
    B = medfilt2(Y,[100 100]); 
    
% % To apply block averaging
     meanFilterFunction = @(theBlockStructure) mean2(theBlockStructure.data(:));
     blockSize = [10 10];
     blockyImage = blockproc(B, blockSize, meanFilterFunction);
     blockyImage(isnan(blockyImage))=0;
     X= pow2db(blockyImage);
     
    
% %   % To save images and their names as a single mat file
     Alpha(k).name=thisBaseFileName;
     Alpha(k).img=X;
    
%    Get lat and lon of blocked images
      R_blocked = R;
      R_blocked.RasterSize = size(X);
%To save georeferencing of all images as a single mat file
     R2(k).name=thisBaseFileName;
     R2(k).Georeferencing=R_blocked;
      
     save('Preprocessed.mat','Alpha', 'R2');
     clear X
      

end
else
end

[Image Analyst]

Because of geotiffread(), it looks like it needs the mapping toolbox or something.