There are many desktop-based tools to work with images. By default, all modern operating systems like Windows, Mac OS and Linux come with a built-in image viewer to enable you preview images without having to install any additional tool.

In Ubuntu Linux, we have a nice tool called Shotwell. This tool replaced F-Spot in 2010 as standard image tool in Ubuntu and other GNOME-based distros. You can do a lot of things with your images using Shotwell like rotating and cropping. You can also instantly reduce the image file size using Shotwell

In some cases, you may need to reduce the image file size for a specific reasons. Whatever your reason, here is how to reduce image file size with Shotwell

• Open your desires image in Shotwell Viewer

• Head to the menu bar and choose File –> Save As. Before saving your image, you will be asked for several additional options including format of your image, quality, pixel and more. To reduce the image file size you can set the pixel with a lower number or set the quality number to the lower percentage. Shotwell offers you 4 percentage options: 100%, 90%, 75%, 50%. If you work with a PNG image you may can consider to switch its format to JPG

Please note that you’ve understood the consequence of changing your image file size. It can affect your image quality