Compression of pictures stored on shared?

Question

PHP

Greetings, in
what ways can I compress and reduce the resolution of images stored on shared hosting?
That is, or can it be done using php (v7) such as GD, or can bash usually have tools to go through all the subfolders? apt-get is blocked.
Thanks to.

Answer 1

Applications can be installed without root, in a local directory, a little more difficult but realistic, something like this
https://askubuntu.com/questions/339/how-can-i-inst...
Install imagemagic and use the solution above
Application in php gd, changing image resolution takes 4 lines plus control
php.net/manual/en/function.imagecopyresized.php