This isn’t a heavyweight image manipulation program like Photoshop or the Gimp. It does some specific things and it does those things very well. It isn’t a replacement; it’s something you can use for doing certain things quickly.
On Windows, it’s very straightforward. Download it and then click on the downloaded file to install it. It’s more difficult on Linux and that’s because there isn’t a Linux version of the program.
The first thing to do is install Wine and you have to install four packages. The first is “Wine”, the second is “wine-mono”, the third is “wine-gecko” and the last one is “winetricks”.
Before doing anything else, run winetricks. You’ll find it in the menu under “Wine”. Once it’s up, leave it with the default choice of “Select the default wineprefix” and click “OK”. On the next pop-up, select “Install a Windows DLL or component” and click “OK”. On the next and last pop-up, select “mfc42” and click “OK”. You can close all the pop-ups when it’s done (“Cancel” works too).
Download IrfanView to your downloads folder and then go to the downloads folder. Right click on the file and then “Open With” and select “Wine Windows Program Loader”. If all goes well, the next pop-up will be the install screen for IrfanView. Don’t bother to set anything. Just install it. When it’s done, just click on the “Done” button.
The file associations work on Windows but not on Linux, so don’t bother trying to set them up. In fact, unless you’re a shell script wizard, you’ll have to load images from within IrfanView. If you always download or store images to a specific folder, it’s easy enough to work with that limitation in place.
I download a lot of images from Pixabay while logged in so I can get the original, full-sized image. I then load an image into IrfanView and shrink the widest axis to 1024 pixels using the “Resize/Resample” option, preserving aspect ratio and applying sharpen after resample. If I need other sizes, I’ll reload the original. I don’t need to sharpen multiple times.
In a project I’m working on, the large image is at 1024 pixels (maximum) and the small image is at 300 pixels wide. I use the small image to link to the larger image.
I can do all of this with the Gimp but it’s faster to do it with IrfanView, especially when doing multiple images.