The need to optimize photos for web loading, combined with the over-compression of some platforms and the subsequent edits by users, can completely ruin the quality of an image. The ideal strategy will always be to seek an intact copy of the original, but we have an alternative: applying different algorithms to "restore" or, why not, improve photo quality.
Improving Photo Quality: "Inventing Pixels"
In essence, algorithms can't do magic. If the compression scheme used in an image is "lossy", there is always a quality sacrifice. What is lost doesn't come back, and in the past we've seen experiments take that loss to extreme levels. However, what algorithms can do is reconstruction, that is, the "creation" of new pixels based on available information.
Over the years, free tools have emerged that do remarkable work. Some specialize in anime or similar content, others prioritize noise reduction, and then there are those that try to combine all benefits. Today we'll review three online services especially prepared to improve photo quality and increase its size, but if you prefer an offline solution, don't worry — we also have something that will interest you.
Waifu2x
The most well-known first, and one we've already covered. The original version of Waifu2x dates back to October 2015, and it applies the full power of convolutional neural networks to improve and enlarge "anime illustrations". Still, it works very well with photos and other types of illustrations. First, you need to specify the image style to process (illustration or photo), how intense the noise reduction should be, and what the resolution increase will be. The web edition of Waifu2x cannot go beyond 2x in resolution.
BigJPG AI Image Enlarger
BigJPG AI Image Enlarger is an alternative based on Waifu2x, but has two additional advantages: it raises the resolution limit to 3000 by 3000 pixels, and it includes upscaling options to 4x, 8x, and 16x (8 and 16x require a premium account). Its interface also allows multiple image uploads, but not batch processing. Privacy note: All images are automatically deleted after 15 days, and download links are encrypted.
IMGonline
Unlike Waifu2x and its variants, IMGonline offers a total of five algorithms to improve photo quality: DCCI (the best, and recommended to start), Lanczos, Mitchell, Quadratic, or Cubic. If compression artifacts are very evident, the site recommends starting with Mitchell or Quadratic. The enlargement support goes up to 16x, and if there's something that separates IMGonline from the rest, it's the possibility to save results in PNG-24 format, without compression.
Bonus track: Waifu2x-caffe
Thanks to Waifu2x's open source profile, offline versions didn't take long to appear, and one of the most popular is Waifu2x-caffe. This version is compatible with Nvidia's CUDA technology, so if you have a graphics card from that company, you'll squeeze out a bit more quality, and most importantly, much more speed during the optimization process. It's not the most intuitive tool in the world, and its parameters can easily overwhelm a modest system, but it definitely deserves your attention.
Alternatives and Conclusion
The best part of all this is that the community doesn't stand still. Online solutions continue to multiply, while users of AMD cards can download Waifu2x editions like Converter-CPP or NCNN-Vulkan, accompanied by the Snowshell frontend that reduces optimizations to a couple of clicks. We hope our recommendations serve you, and if you have another to share, leave a comment! Good luck!.
