Resize photos by imagemagick

add_overlay.sh

size=50
mkdir converted
find . -type f -maxdepth 1 -print0 | \
    xargs -0 -n 1 -P 8 -I __FILE__ \
    convert __FILE__ -resize $size -set filename:new '%d/%t' \
    \( -clone 0 -tile overlay.png -draw "color 0,0 reset" \) \
#    -compose blend -define compose:args=50 \
    -compose overlay \
    -composite "converted/%[filename:new]_${size}.png"

resize.sh

rm -rf converted
mkdir converted

# Resize to width=16px
find . -type f -maxdepth 1 -print0 | \
    xargs -0 -n 1 -P 8 -I __FILE__ \
    convert -resize 16 -set filename:new '%d/%t' __FILE__ 'converted/%[filename:new]_16.png'; 

cd converted
rm -rf converted
mkdir converted

# Resize back to 130 with smoothing
find . -type f -maxdepth 1 -print0 | \
    xargs -0 -n 1 -P 8 -I __FILE__ \
    convert -resize 130 -set filename:new '%d/%t' __FILE__ 'converted/%[filename:new]_130.png'; 

# Resize back to 130 in pixels
find . -type f -maxdepth 1 -print0 | \
    xargs -0 -n 1 -P 8 -I __FILE__ \
    convert -resize 130 -filter Point -set filename:new '%d/%t' __FILE__ 'converted/%[filename:new]_130_pixels.png'; 

cd ..