PVRTC -I and -II are a family of lossy, fixed-rate texture compression

Texture compression

Texture compression is a specialized form of image compression designed for storing texture maps in 3D computer graphics rendering systems. Unlike conventional image compression algorithms, texture compression algorithms are optimized for random access....

 formats used in PowerVR

PowerVR

PowerVR is a division of Imagination Technologies that develops hardware and software for 2D and 3D rendering, and for video encoding, decoding, associated image processing and Direct X, OpenGL ES, OpenVG, and OpenCL acceleration....

's MBX and SGX technologies. The PVRTC-I algorithm is documented in Simon Fenney's paper "Texture Compression using Low-Frequency Signal Modulation" that was presented at Graphics Hardware 2003.

These differ from block-based texture formats such as S3TC and Ericsson Texture Compression

Ericsson Texture Compression

Ericsson Texture Compression is a texture compression technique developed in collaboration with Ericsson Research in early 2005. It was originally developed under the name iPACKMAN and based on an earlier compression scheme called PACKMAN.The original 'ETC1' compression scheme provides 6x...

 (ETC) in that the compressed image is represented by two lower resolution images which are bilinearly upscaled and then blended according to low precision per-pixel weights. They also differ in that they support ARGB data in both 4-bpp and 2-bpp modes.

PVRTC is the compressed texture format used in all generations of the iPhone

IPhone

The iPhone is a line of Internet and multimedia-enabled smartphones marketed by Apple Inc. The first iPhone was unveiled by Steve Jobs, then CEO of Apple, on January 9, 2007, and released on June 29, 2007...

, iPod Touch

IPod Touch

The iPod Touch is a portable media player, personal digital assistant, handheld game console, and Wi-Fi mobile device designed and marketed by Apple Inc. The iPod Touch adds the multi-touch graphical user interface to the iPod line...

, and iPad

IPad

The iPad is a line of tablet computers designed, developed and marketed by Apple Inc., primarily as a platform for audio-visual media including books, periodicals, movies, music, games, and web content. The iPad was introduced on January 27, 2010 by Apple's then-CEO Steve Jobs. Its size and...

.