image optimization for websites

refer: https://jmperezperez.com/jpegoptim-optimize-jpg-page-speed/

jpegoptim
smushit for wordpress

In my opinion the best option out there that effectively handles most image formats in a go is trimage. It effectively utilizes optipng, pngcrush, advpng and jpegoptim based on the image format and delivers near perfect lossless compression.

The implementation is pretty easy if using a command line.

sudo apt-get install trimage    
trimage -d images/*

I use jpegoptim to optimize JPG files and optipng to optimize PNG files.

If you're on bash, the command to losslessly optimize all JPGs in a directory (recursively) is:
find /path/to/jpgs/ -type f -name "*.jpg" -exec jpegoptim --strip-all {} \;


You can add -m[%] to jpegoptim to lossy compress JPG images, for example:
 find /path/to/jpgs/ -type f -name "*.jpg" -exec jpegoptim -m70 --strip-all {} \;


To optimize all PNGs in a directory:
find /path/to/pngs/ -type f -name "*.png" -exec optipng -o2 {} \;


-o2 is the default optimization level, you can change this from o2 to o7. Notice that higher optimization level means longer processing time.

optimize() {

  jpegoptim *.jpg --strip-all

  optipng -o7 -preserve *.png

  for i in *

  do

    if test -d $i

    then

      cd $i

      echo $i

      optimize

      cd ..

    fi

  done

  echo

}

optimize