Re: Image registration/averaging and image quality
- From: Jerry Avins <jya@xxxxxxxx>
- Date: Wed, 05 Jul 2006 12:34:23 -0400
Piotr wrote:
1) In the ideal case the registration and averaging of, for instance
150 individual 8bit noisy images will improve SNR by log10(n x 256),
Where does that come from? for one dimension and white Gaussian noise, the improvement is not log10(256*n), but sqrt(n). That yields improvement by factor of 16, or 12 dB.
and the dynamic range from ~2.4 to ~4.6. However, when aligning low SNR
images, the match is not always perfect (or rather, it is almost never
perfect). Under such circumstances how does one model the change in
SNR.
2) Is there a better metric to characterize the improvement in
resolving power, or resolution, when registering and averaging multiple
frames
Noise and resolution are not exactly related. Under some unlikely circumstances, you could gain 4 bits of resolution.
If your 8-bit converter had the linearity of a 12-bit, and the noise happened to simulate a nearly ideal dithering waveform, and signal were stationary during the averaging process, then the average of 256 conversions would be accurate to 12 bits. How that affects the resolution of an image would be better answered in another group.
Jerry
--
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