You can sharpen an image in GIMP on your computer using the Sharpen tool or the Sharpen filter. Here is a full tutorial on how to do it!

Select the image you want to resize, using the Open Image file browser, and click the "Open" button to open the image in GIMP.

GIMP, a free, open source image editor, that’s available for Windows, OS X, Ubuntu, Debian, openSUSE, Fedora, Mandriva, BSD, and Solaris and one of its neat features is an automation plugin ...

GNU Image Manipulation Program is a free open-source image manipulation software, GIMP has features and tools that make it a fierce competitor with some paid high-end image manipulation software.

Click GIMP's "File" heading and select the "Open" option from the menu that appears. Load the image that you wish to stretch, using the file explorer window. Click the "Image" heading.

Discover Batcher, the powerful batch-editing plugin designed for GIMP 3.0. Easily convert file formats, export layers, and apply custom actions to streamline your creative workflow.

The GIMP is an open source software application for editing raster graphics. It is intended to serve as a free and open alternative to high-end image editing programs for a professional audience.