Resizing pictures

I wanted to resize a jpeg emailed to me on my Raspberry Pi 4 (a nephew’s new baby). The default Image Viewer on Raspberry Pi OS will rotate but not resize. I googled and found a four-year-old article in the Raspberry Pi Magazine about a software package called Mirage which sounded ideal, as I did not fancy wrestling with the monstrous Gimp. I installed Mirage but it crashed with a segmentation fault when I tried to run it (needs recompiling for the Rpi4 maybe?). But then I found the website https://www.resizepixel.com which did all that I needed, so why bother with installing client-side software? Sadly it does not work with NetSurf, so I cannot use it from RISC OS.

What about ChangeFSI? Or DplngScan?

I use !ChangeFSI to resize the huge pictures my daughter sends to me.

Change the save output from Sprite to JPEG and use zoom to scale the image.

For raspi images I use VNC from RISC OS then PrivateEye to scale and rotate. Then use Snapper to capture contents of window as a jpeg.

I find !Variations works well on RISC OS, you can easily adjust gamma, saturation and contrast levels as well as resize, should you wish to do so.
http://compo.iconbar.com/variation.htm