Convert a bunch of artboards in grayscale.

grayscale_artboards.sh

#!/bin/bash

folder_artboards="./artboards"
folder_grayscale="./grayscale"
folder_grayscale_opt="./grayscale_opt"

# find $folder_grayscale -name "*.png" -type f -delete

for i in $(find $folder_artboards -name "*.png" -type f);
do
    base_name=$(basename "$i")
    date_source=`stat -f "%Sm" -t "%Y%m%d%H%M.%S" "$folder_artboards/$base_name"`

    if [ -f "$folder_grayscale/$base_name" ];
    then
        date_grayscale=`stat -f "%Sm" -t "%Y%m%d%H%M.%S" "$folder_grayscale/$base_name"`
        if [ "$date_source" == "$date_grayscale" ];
        then
            echo "Skip :: $base_name"
            continue
        fi
    fi

    # Imagemagick has some nice filters for gray scale
    convert \
        "$folder_artboards/$base_name" \
        -grayscale rec601luma \
        "$folder_grayscale/$base_name"

    # In the process let's scale the image
    convert \
        "$folder_grayscale/$base_name" \
        -resize 50% \
        "$folder_grayscale/$base_name"

    # Up to you to crush the png size
    #pngcrush -reduce -brute "$folder_grayscale/$base_name" "$folder_grayscale_opt/$base_name"

    touch -t "$date_source" "$folder_grayscale/$base_name"
    echo "Created :: $base_name"

done