Upscaling (free, not freemium)
Tried, it works
Image Super-Resolution [upscaling] for Anime-style [low detail] art or images using Deep Convolutional Neural Networks.
Web App Online web app [using the same library] provided at http://waifu2x.udp.jp/.
Command Line Program Command line tool with integrated software library to upscale images and apply post processing. Utilizes either CPU (extremely slow and resource intensive) or Nvidia GPU (fast with CUDA acceleration) for upscaling.
A Sharper Scaling is a high quality image scaling technology mainly developed for upscaling.
Didn't try yet
An image, gif and video upscaling and denoiser app developed with electron, react, waifu2x and ffmpeg.
Waifu2x Caffe rewrites only the conversion function of the image conversion software "waifu2x" using Caffe and is software developed for Windows. Although it can convert with CPU, using CUDA (or cuDNN) can convert faster than CPU. GUI supports English, Japanese, Simplified Chinese, Traditional Chinese, Korean, Turkish, Spanish, Russian, and French.
What is the principle of enlarging?
Using the latest Deep Convolutional Neural Networks(based on waifu2x). It intelligently reduces noise and serration in images to enlarge them without losing quality. See demo images
Uploaded images and enlarged images will be automatically deleted after 15 days. Image links are encrypted, unless you share it yourself, or else other people can nott download the image.