CHDK

Digital Imaging Integrated Circuit is Canon Inc.'s name for a family of signal processing and control units for digital cameras and camcorders. DIGIC units are used as image processors by Canon in its own digital imagery products. Several generations of DIGICs exist, and are distinguished by a version number suffix.

Currently, DIGIC is implemented as an application-specific integrated circuit (ASIC) designed to perform high speed signal processing as well as the control operations in the product in which it has been incorporated. Over its numerous generations, DIGIC has evolved from a system involving a number of discrete integrated circuits to a single chip system, many of which are based around the ARM instruction set. Custom firmware for these units has been developed to add features to the cameras.

The original DIGIC was used on the PowerShot G3 (Sep 2002), Canon S1 IS (Mar 2004), A520 (Mar 2005), and other cameras. It consists of three separate chips: a video processing IC, an image processing IC and a camera control IC.

DIGIC II is a single chip system introduced in 2004, unlike the first DIGIC, that allowed for more compact designs. DIGIC II also improved upon the original by adding a larger buffer and increasing processing speed. It has been used in some advanced consumer-level cameras and many discontinued digital SLRs such as Canon EOS 5D and Canon EOS 30D.

DIGIC II uses high-speed DDR-SDRAM, which improves startup time and AF performance. It can write to memory card at speeds up to 5.8 MB/sec. Additionally, Canon claims DIGIC II improves color, sharpness, and automatic white balance with its CMOS sensor in its digital SLR camera line.

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