I have just tested A.I. Gigapixel, a $99 software package of Topaz Labs supposedly using artificial intelligence to resize images up to 600 percent without significant loss of quality. Well, it did not work for me.
Image processing is prohibitively slow. All my attempts to resize even a small web size image of 800×600 beyond 200 percent resulted in freezing up the application. Also when my patience has been rewarded with sized up image after a half-hour long processing the image quality was not significantly better then quick scaling up in Gimp with some smoothing/sharpening in Lightroom. The miracle did not happen.