EIR - Easy Image Resizer
Easy Image Resizer for Joomla! automatically resizes the resolution of images which are uploaded through the Media Manager. This is often useful if images are not previously processed offline and uploaded in a too large resolution.
The automatic resizing also reduces the size of the images, which can lead to serious performance improvements of the loading time. The plugin is executed directly when uploading images in the media manager and the 'Image' button in the edit mode.
Easy Image Resizer implements the service by Optimus.io for a lossless compression of images. Use this feature to get even better results!
With the option "Safe Image Names" the image names are converted to make them safe for the upload process. UTF8 characters are encoded to ASCII, special characters are removed, whitespaces are replaced with underscores and the resulting string is converted to lowercase.
Joomla! 3 - https://joomla-extensions.kubik-rubik.de/downloads/eir-easy-image-resizer/joomla-3
The extension is completely free, but you need a subscription for support: