ISO Sensitivity / Noise levels (contd.)

In-camera High ISO noise reduction

The A350 offers a simple on/off option when it comes to High ISO noise reduction. Unusually, this additional noise reduction attempts to address both chroma and luminance noise. As you can see, it has no effect up to ISO 800 where the plots overlap each other almost exactly, before kicking-in at ISO 1600 and 3200. The results, visible in the stamp crops below, show that this noise reduction is impacting more than ever on the image quality, with the ISO 3200 results looking more like compact camera output than the results we'd expect a DSLR to produce (albeit at a very high ISO).

Indicated ISO sensitivity is on the horizontal axis of this graph, standard deviation of luminosity on the vertical axis.

Noise reduction crop comparisons (ISO 800 - 3200)

Off ISO 800	On ISO 800	EOS 450D (NR ON) ISO 800
Off ISO 1600	On ISO 1600	EOS 450D (NR ON) ISO 1600
Off ISO 3200	On ISO 3200

Noise reduction on RAW image files

With its A700 flagship, Sony made the controversial move of applying a degree of noise processing to the data before it was saved as a 'RAW' file. Here we compare the results of the A350 with High ISO noise reduction turned off. There is still some noise reduction clearly being applied to the JPEG results (the size and smoothness of the chroma noise blotches being a distinct give-away). Thankfully these are not apparent in the RAW files, suggesting that either Sony has had a change-of-heart or that the technology was in some way specific to its processing pipeline for the CMOS sensor featured in the A700.

RAW files converted using Adobe Camera Raw with noise reduction set to 0, saved as a quality 11 JPEG for cropping.

DSLR-A350 JPEG ISO 1600	DSLR-A350 RAW NONR ISO 1600	Pentax K20D RAW ISO 1600
DSLR-A350 JPEG ISO 3200	DSLR-A350 RAW NONR ISO 3200	Pentax K20D RAW ISO 3200