No, Xnview doesn't work. No, renaming the file extension doesn't work. And NO, using the hex format via text file will not work, either. If none of these mentioned options jump out at you, don't fret, they don't work anyway.
But there is hope, and it's in the simple form of a very unique script, written by RobA. It's called Sample Gradient Along A Path, and can be found here.
Don't understand how to install scripts? No problem, read here.
Ok, now back to the gradients, and RobA's gem of a script:
The next best thing is finding an image of the gradient you want. There are many gradient images on the internet, most are small, but they will still work with this script. I typed :"PS gradients" searching under Images and found several. The gradient I was looking for was similar to metallic tubing, like copper, gold, or aluminum.
How to use the script:
Open any of the gradient images in GIMP, and select the Path tool. Set a Path across the gradient (like shown):
That's it! You're done. Enjoy your new PS style gradient. :)