SNR & Drizzle

[Dimitris Platis]

What is the effect of Drizzle on SNR?
Is there any real advantage in Drizzling 3x over 2x?

[RickS]

What is the effect of Drizzle on SNR?

If you upsample with Drizzle you lose SNR.  There's no free lunch.  However, the noise is correlated between neighboring pixels and isn't as visible (IMO, at least) or as easy to measure using the standard tools in PI.  Some info here: http://www.stsci.edu/hst/HST_overview/documents/multidrizzle/ch34.html#385457

Is there any real advantage in Drizzling 3x over 2x?

Yes, it will give you higher resolution but only if the seeing, optics and quality and amount of data is adequate.

Cheers,
Rick.

[jkmorse]

But remember, going from 2x to 3x requires a lot of quality data and will make the image huge (9 times the size of the original as compared to 4 times with 2x).  I have played with both but for image stacks of even 60 subs, I do not see any difference that justifies the huge file size.

[Dimitris Platis]

I have 150-300 subs depending on the channel.....so I have a lot of data.
But I havent seen any improvement going from 2x to 3x