rename szi images to make them easily imagemagick-able

szi-montage.zsh

#!/bin/zsh

# szi file[1] setup is:
#
#   col_row.jpg
# 
# for imagemagick we want: 
#
#   row_col.jpg
#
# and make sure to pad numbers for lexicographical sorting. 
# 
# [1] https://github.com/smartinmedia/SZI-Format


for file in *.jpg; do
    # =~ is the regex matching operator in zsh 
    if [[ $file =~ ^([0-9]+)_([0-9]+)\.jpg$ ]]; then
        col=${match[1]}
        row=${match[2]}
        
        # Pad col and row with leading zeros to ensure triple digits sorting
        col=$(printf "%03d" $col)
        row=$(printf "%03d" $row)
        
        # swap col and row, and add r_, c_ to make sure files don't overwrite each other 
        new_file="r${row}_c${col}.jpg"
        
        cp "$file" "$new_file"
        echo "Renamed $file to $new_file"
    fi
done

# call imagemagick with:
# magick montage -mode concatenate -tile 82x r*.jpg ../montage.jpg