hqx

The title of this article is ambiguous. Further meanings are listed under HQX .

hqx is an algorithm in the image processing for the scaling of pixel graphics or sprites .

It was developed by Maxim Stepin . The algorithm is relatively fast because it is based internally on lookup tables and can therefore be used in real time without any problems. It is mainly used in emulators like Nestopia , Snes9x , VisualBoyAdvance and ZSNES .

There are currently three magnification factors : hq2x , hq3x , and hq4x (2 ×, 3 × and 4 ×). For other sizes, the algorithm is used in combination with a nearest neighbor (“nearest neighbor”) interpolation.

Image enlarged by a factor of 3 with a nearest neighbor interpolation

Image enlarged by a factor of 3 with the hq3 filter

See also

• Scaling (computer graphics)
• Sprite (computer graphics)
• Pixel art

Web links

• Demos & Docs - hq2x Magnification Filter ( Memento from December 5, 2013 in the Internet Archive )

  Demos & Docs - hq3x Magnification Filter ( Memento from November 14, 2013 in the Internet Archive )

  Demos & Docs - hq4x Magnification Filter ( Memento from December 16, 2013 in the Internet Archive )

• hqx project at code.google.com
• Butchering HQX scaling filters How the algorithm works