I've just integrated a fantastic filter for upscaling images called Waifu2x.

Here's a small-res original image:
   


Here it's upscaled 4x using FILTER_LINEAR:
   


Here upscaled 4x using my own cubic filter (FILTER_CUBIC/FILTER_BEST), which was already quite good:
   


And now.. get ready for some magic, here is 4x FILTER_WAIFU:
   

dang, that is indeed pretty cool

Wonderful tool for moving existing HD art to 4K graphics.
I haven't tried it yet though likely it will not work perfectly on tileable textures? I can only imagine that tileable textures would likely require additional processing (pre and post filter) to reduce the seams - something like making a 3x3 grid filled with copies of the image that is being up-scaled and do a waifu2x on this entire grid-image only to, then, cut the middle copy out?

It will work very well on tiled textures

For material textures default mode is wrap.
For Image Project Elements default mode is clamp.

You can manually control clamping by using
"?resizeClamp=2x"
or
"?resizeWrap=2x"

Wow! That's some impressive upscaling algorithm and a nice addition.