This is what ended up working for me:
meta1='{"Length":'
meta2=',"Height":"'
meta3='"}'
while IFS=$'\t', read -r col1 col2 col3 col4 col5 || [ -n "$col1" ]
do \
meta=$meta1
meta+=$col4
meta+=$meta2
meta+=$col5;
meta+=$meta3
And for meta_input line
--meta_input=$meta \