Here. I'm sure there are better ways, but it seems to be simple enough that I can get away with directly editing the file.
% document is zipped so that the forum editor allows it; unzip it
unzip('Testing.zip')
% document itself is a zip archive; unzip it to a temp directory
tempdir = 'docxdump';
unzip('Testing.docx',tempdir)
% get the location of the embedded images
dirinfo = dir(fullfile(tempdir,'word/media/*.png'));
nfiles = numel(dirinfo);
% crop them and put them back
for k = 1:nfiles
thisfname = fullfile(dirinfo(k).folder,dirinfo(k).name);
thispict = imread(thisfname);
thispict = imcrop(thispict,[108 194 1263 710]);
imwrite(thispict,thisfname);
end
% take the contents of the temp directory and re-zip it
outfilename = 'modified';
dirinfo = dir(fullfile(tempdir,'*'));
dirinfo = dirinfo(~ismember({dirinfo.name},{'.','..'}));
zip([outfilename '.docx'],{dirinfo.name},tempdir)
movefile([outfilename '.docx.zip'],[outfilename '.docx'])
% remove the temp directory
rmdir(tempdir,'s')
At least that works in this simple case. The image objects are simply scaled to fit the same existing rectangular region in the document. If the cropped images had an aspect ratio that differed from the uncropped images, there would be problems.
