#!/bin/bash
 
echo -n "Enter the width of resize in pixel : "
read size
echo -n "Name of folder you want to resize : "
read foldername
 
# populate the array
while IFS='' read -r -d '' file; do
array+=("$file")
done < <(find . \( -iname "*.jpg" -o -iname "*.jpeg" -o -iname "*.tiff" -o -iname "*.png" -o -iname "*.gif" -o -iname "*.bmp" \) -type f -print0)
 
# loop through all elements
for ((i=0; i<${#array[*]}; i++)); do
dir=${array[i]%/*}
name=${array[i]##*/}
if [[ ! -d "$dir/$foldername" ]]; then
 mkdir "$dir/$foldername"
fi
echo converting "${array[i]}"
convert "${array[i]}" -adaptive-resize $size "$dir/$foldername/thumbnail_$name"
done
 
exit 0