MMPX Style-Preserving Pixel Art Magnification
Author
Venue
Journal of Computer Graphics Techniques
Abstract
We present MMPX, an efficient filter for magnifying pixel art, such as 8- and 16-bit era video-game sprites, fonts, and screen images, by a factor of two in each dimension. MMPX preserves art style, attempting to predict what the artist would have produced if working at a larger scale but within the same technical constraints. Pixel-art magnification enables the displaying of classic games and new retro-styled ones on modern screens at runtime, provides high-quality scaling and rotation of sprites and raster-font glyphs through precomputation at load time, and accelerates content-creation workflow. MMPX reconstructs curves, diagonal lines, and sharp corners while preserving the exact palette, transparency, and single-pixel features. For general pixel art, it can often preserve more aspects of the original art style than previous magnification filters such as nearest-neighbor, bilinear, HQX, XBR, and EPX. In specific cases and applications, other filters will be better. We recommend EPX and base XBR for content with exclusively rounded corners, and HQX and antialiased XBR for content with large palettes, gradients, and antialiasing. MMPX is fast enough on embedded systems to process typical retro 64k-pixel full screens in less than 0.5 ms on a GPU or CPU. We include open source implementations in C++, JavaScript, and OpenGL ES GLSL for our method and several others.