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Messages - Dimitris Platis

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16
Here's my quick and dirty version

17
What exactly r u looking for? Something like this?
Unfortunately, the small size creates significant artifacts of color and luminance...but u get the idea.

18
General / Re: Noise vs Mosaics....Rule of thumb
« on: 2016 February 19 07:38:06 »
In that case I guess its a matter whether i prefer higher snr with lower resolution or lower snr with higher resolution.

19
General / Re: Noise vs Mosaics....Rule of thumb
« on: 2016 February 18 10:07:13 »
Yes Mike....that was my original suspicion and indeed there must be a lower integration time required to avoid problems...eg alignment

20
General / Re: Noise vs Mosaics....Rule of thumb
« on: 2016 February 18 04:00:22 »
Yes...the way I see it...u can either shoot a mosaic so u can have a high resolution widefield image....OR....u can shoot a mosaic because of relatively high focal length in which case u can downsample. In most cases, u wont be able to take advantage of the high resolution because most images are depicted on a PC screen or even when printed u will never have a large enough image to really display the true resolution of your image.

It is a shame.....but in many cases a mosaic its just a way to get over the obstacle of long focal length.

21
General / Noise vs Mosaics....Rule of thumb
« on: 2016 February 18 02:30:50 »
Does anyone know a general rule of thumb regarding exposure time in mosaics?......meaning that surely we can get away with less integration time per pane the more panes u get in mosaics since the noise is obscured in a way by the oversampling of the imaged area compared to the actual resolution of the complete photo.

 

I hope its clear what I mean...

22
General / Re: mosaic STF problem
« on: 2016 February 08 23:00:26 »
Thats because u havent clicked frame Adaptation during the registration process and the 2 frames havent been linear fitted.

23
IS this image from a corner of your image?
It looks like coma to me

24
General / Re: How to use rgb stars in a narrowband image?
« on: 2016 January 08 10:18:44 »
U can really use narrowband stars with excellent results (no magenta) as long as u dot the following.,,,
1) Remove stars by Structure map + Morphological Transformation
2) Create Difference Map
3) Linear fit all filters (Ha, OIII, SII)
4) Add stars to each filter
5) SHO script

25
Image Processing Challenges / Re: light pollution challenge
« on: 2016 January 06 12:08:09 »
Its not a problem for DBE to get rid of it.
But do u image with CCD or DSLR?

26
At the completed Drizzled image state I agree it is difficult to estimate SNR.....however, I must say that even at Variance 0.8 (tested with a Heart and Soul image) no loss or blurring if u wish of structures where observed.
The noise reduction seemed to be done correctly in a manner that seemed natural and not artificial.

27
How exactly would u measure loss of SNR for different Variances?

28
I should add that testing the effects of the script in a Drizzled image (variance 0.8, and Noise taken from bias) I had a significant noise reduction.
Perhaps its worth just testing different parameters of the scripts at random even in Drizzled images

29
General / Re: SNR & Drizzle
« on: 2015 December 17 08:53:29 »
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

30
General / SNR & Drizzle
« on: 2015 December 16 22:50:58 »
What is the effect of Drizzle on SNR?
Is there any real advantage in Drizzling 3x over 2x?

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