How to resize multiple images at once in Ubuntu 14.10/Ubuntu 14.04. Download and install Simple Image Resizer (SIR) on Linux (Ubuntu 14.10 and Ubuntu 14.04) for batch resizing, rotating and converting images.
SIR is an open source tool written in C++ and created via the Qt GUI toolkit. It can also for adding frames or text on images. It can be used for basic editing tasks such as to apply color and gradient filters to the images. The application supports various file formats including: JPEG, JPG, PNG, GIF, BMP, XPM, PGM, PBM and PPM and RAW.
sudo apt-add-repository ppa:dhor/myway
sudo apt-get update
sudo apt-get install sir
If you wish to uninstall and remove the Simple Image Resizer from Linux Ubuntu systems, run the following command in Terminal:
sudo apt-get remove sir