Canon's CMOS (complementary metal oxide semiconductor) sensor captures images with exceptional clarity and tonal range, and offers the most pixels in its class. It offers many of the same new technologies to maximize each pixel's light gathering efficiency that were first seen with the professional EOS-1D Mark III model. It's an APS-C size sensor (22.2 x 14.8mm), and there's an effective 1.6x increase in the lens's marked focal length when attached. Canon's DIGIC III Image Processor dramatically enhances image quality and speeds up all camera operations for intuitive operation. It works in concert with the EOS Rebel XSi's sensor to achieve unprecedented levels of performance in all lighting situations.
12.2 Megapixel APS-C Size CMOS Sensor
14-bit A/D Converter
With the EOS Rebel XSi, analog to digital signal conversion is executed by a 14-bit processor, which generates digital data with incredibly smooth tones. Formerly a feature only present in top-of-the-line pro digital SLR cameras, the 14-bit conversion gives incredibly smooth transitions from light to dark colors, with far less risk of "banding." A sky at sunset is a perfect example. With this rich 14-bit gradation the EOS Rebel XSi offers RAW images of the highest quality that can be processed with Canon's Digital Photo Professional software. Even JPEG files, which are always finished at 8-bits per channel, use the full 14-bit conversion initially to generate the best possible color and tonal detail. Another huge benefit of the 14-bit conversion is the Highlight Tone Priority option, which allows critical shooters to increase the level of detail in bright areas of a scene up to one stop, without affecting overall exposure.
The EOS Rebel XSi's Auto Optimization is yet another image-quality tool that comes to the rescue in tricky lighting conditions. It can actually lighten dark areas of a scene while ensuring that bright areas maintain tonal detail. It's now available in all shooting modes, including P, Tv, Av, and Manual.
DIGIC III Image Processor
Developed to maximize performance between the capture and recording stages of digital photography, the EOS Rebel XSi's latest-generation DIGIC III Image Processor works in concert with Canon's CMOS sensor to achieve even higher levels of performance. The entire electronic system is totally redesigned, giving the camera its incredible combination of speed and image quality. Digital noise is significantly reduced in shadow areas, and color reproduction is superior.