To compress your images from the Linux command line, you’ll need two programs — one for *.jpg file types and one for *.png file types.
- jpegoptim (for *.jpg file types)
- optipng (for *.png file types)
Compress JPG
To install jpegoptim:
$ apt-get install jpegoptim
To compress all *.jpg files in a directory:
$ jpegoptim -m 50 *.jpg
The command-line switch “-m 50” disabled lossless compression.
-m<quality>, –max=<quality>
set maximum image quality factor (disables lossless optimization mode, which is by default on)
valid quality values: 0 – 100
If you’d prefer to maintain lossless, remove this switch.
Compress PNG
To install optipng:
$ apt-get install optipng
To compress all *.png files in a directory:
$ optipng *.png
Source(s): TecMint