For debugging purposes, please try
csfilename = fullfile(csfigs, [csname '.jpg']);
csfigs_image = imread(csfilename);
img = imshow(csfigs_image);
ax = ancestor(img, 'axes');
I suspect that you will still get the message but associated with the imread() call. This will, however, help us isolate whether the problem is coming from imshow or from the reading process.
