Using 'convert' from Image Magick from Gambas.

This is a Q&D (Quick & Dirty) application that uses the command line application convert from ImageMagick to resize images by percentage (%)
I mainly use it to quickly reduce (camera) images to something that much smaller to send 'happy snaps' to family via email.

Not translated, so some folder names are hard coded in English - should be a quick and easy change.
 
If you right click on an image file, you can select to View the image in the app, Copy it to your Pictures folder, Delete or Open in your system default image application (Normally an image viewer ?)

Note# If you choose to display the image you can move it out of the way with a simple drag. 

ImageResize.tar.gz

 

I downloaded your app, It works well, the Cancel button doesn't do anything, but I wondered, as a Linux Mint user, have you not found the add-on for Nemo to do this? Just run the code below to install the necessary, then log out and back in.

 

Thanks Cogier.
Told you it was (Quick & Dirty) - I've added the Me.Close to the cancel button click event. Attached for those interested.

ImageResizeV2.tar.gz

I've been using Mint for a very long time and have never heard of the nemo add-on. I'll check it out.
Without installing it yet, the only advantage to mine is that you can do bulk files, but that's only really useful for a few niche use cases.

Quincunxian said

..the only advantage to mine is that you can do bulk files…

The Nemo app can also deal with multiple files. I use it for posting holiday photos on my website. I reduce them from up to 6.0MB to 200kb.