Super-Resolution

Super-resolution is the process of recovering a high-resolution (HR) image from a low-resolution (LR) image. It's essentially using deep convolutional neural networks in deep learning to upscale images. The basic idea is to make an imagine look better, whether it is done by making the image bigger, improving image quality, or removing noises. There are many softwares out there that does something like that without the user even knowing! Popular upscaling softwares include GIMP, Photoshop, Gigapixel AI, and Waifu2x. Of those popular upscalers, Gigapixel AI is arguable one of the best paid software for upscaling, while Waifu2x is the best free alternative. This site will be talking about Waifu2x and the alternatives based on Waifu2x.

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Traditional Upscaling vs AI Upscaling

What is Upscaling?

Upscaling is a technique used to obtain a higher resolution video or image by converting a lower resolution media to a higher resolution media. Traditional upscaling doesn't necessarily generate a higher quality of that media(video or image), in fact it could generate a media with even worse quality as all a upscaler needs to accomplish is to enlarge it to the user's specified resolution. The basic requirement to qualify as a upscaler is to just have a low resolution media fill up said resolution on your monitor. With the advancement of AI and the popularity of machine learning, deep learning (a subfield of machine learning) became extremely popular for upscaling softwares. To understand how deep learning enhances upscaling quality the information can be obtained from this Medium article.

List of Video Resolutions

  • 240p = 426x240
  • 360p = 640x360
  • 480p = 854x480
  • 720p = 1280x720
  • 1080p = 1920x1080
  • 1440p = 2560x1440
  • 2160p or 4K = 3840x2160
  • 8k or 4320p = 7680x4320
video_resolutions
Video Resolution Chart

What is Denoising?

Denoising is the process of removing noise from a media(video or image).

A formal definiton for image noise is the random variation of brightness or color information in images, and is usually an aspect of electronic noise. It's essentially the grainy looking veil obscuring the picture making it look awful.

periodic_noise_example
Example of periodic noise(a type of interference noise) on the left.
Image via PremiumBeat.

Waifu2x and Gigapixel AI

Having gone through basic ideas of upscaling and denoising to get that perfect image, what softwares provide great upscaling and denoising? Both Waifu2x and Gigapixel AI are great contenders for being the best softwares to achieve great looking images via super-resolution imaging. So, what's the difference between the two?

gigapixel icon
Gigapixel AI
  • Paid Software
  • Best for 3D images
  • Limited to supporting up to 600x scale
  • The software only supports Window and Mac OS
  • Learning curve for using the software is smaller due to its intuitive GUI
waifu2x icon
Waifu2x
  • Open-source and free
  • Best for 2D images
  • Limited to supporting up to 2x scale
  • The demo application works on every platform, but the actual software is only available on Linux
  • CLI based and so has a much higher learning curve to use the software

Gigapixel AI the Clear Winner?

There's a pretty good reason why Gigapixel AI is a paid software as it is a pretty great software overall. The greatest difference between the two would be the type of images it works best with; Gigapixel AI working better with 3D images or photography, while Waifu2x works best with 2D images or hand drawn images. Waifu2x has a demo application hosted on their website so platform compatibility isn't as big a concern. The Waifu2x site also has a simple yet limited interface if user's don't want to get into working with the command line interface(CLI).

A temporary solution to Waifu2x's weakness is to use their website, but the best and greatest thing about Waifu2x is the fact that it's a free open source project! In short there are many third party softwares based off Waifu2x, thus solving many of it's inherent limitations. Popular third-party softwares/projects based off Waifu2x includes Waifu2x-Caffe, Waifu2x-Converter-CPP, Waifu2x-NCNN-Vulkan, Anime4K, Video2x, Dandere2x, and the list goes on!

In short if Waifu2x falls short of what satisfies your needs, then other third-party softwares/projects will do just as well, if not better! It should be noted that Waifu2x's last release was in 2018, which is why many third-party softwares/projects are generally recommended over Waifu2x. Popular third-party softwares include Waifu2x-Caffe, Waifu2x-NCNN-Vulkan, Waifu2x-Converter-CPP, and Video2x.

This website will go over a more basic overview of Waifu2x, Waifu2x-Caffe, and Video2x with examples and comparisons.