Recursively optimize all PNG and JPG files wherever they are from the script position and inner ( based on OPTING, PNGCRUSH, ADVANCECOMP and JPEGOPTIM )

pagespeed_optimize_images.sh

#!/bin/bash
find . -type f -name "*.png" -o -name "*.PNG" | xargs optipng -nb -nc
find . -type f -name "*.png" -o -name "*.PNG" | xargs advpng -z4
find . -type f -name "*.png" -o -name "*.PNG" | xargs pngcrush -rem gAMA -rem alla -rem cHRM -rem iCCP -rem sRGB -rem time -ow
find . -type f -name "*.jpg" -o -name "*.JPG" | xargs jpegoptim -f --strip-all

## Log to file
# find . -type f -iname "*.png" -print0 | xargs -I {} -0 optipng -o5 -quiet -keep -preserve -log optipng.log "{}"

If you wish to compress some file in 5 minute with 70% max quality just type like below

find . -mmin -5 -type f -name "*.jpg" -o -name "*.JPG" | xargs jpegoptim -m70 -f --strip-all -p

Crontab for run every 5th minutes.

*/5 * * * * find /path/to/images/directory/ -mmin -5 -type f -name "*.jpg" -o -name "*.JPG" | xargs jpegoptim -m70 -f --strip-all -p \; > /dev/null

How to resize image with same quality

find . -type f -size +1M | xargs -i{} convert -resize 50% {} {}