We shoot a specially designed chart in carefully controlled conditions and the resulting images are analysed using the DXO Analyzer software.
Signal to noise ratio
A high signal to noise ratio (SNR) indicates a cleaner and better quality image.
JPEG images from the Leica M9 show less noise throughout the sensitivity range than the Sony Alpha 900. Despite the M9 producing a similar signal to noise ratio as the Nikon D700 at ISO 3200, at all other values the D700, and Canon EOS 5D MK II both show better handling of noise.
This chart indicates that the Leica M9's JPEGs have a at least a 1.5EV lower dynamic range than the comparison cameras JPEG files across the sensitivity range.