#1  
Old 31-07-2014, 11:36 PM
Amaranthus's Avatar
Amaranthus (Barry)
Thylacinus stargazoculus

Amaranthus is offline
 
Join Date: Jan 2014
Location: Judbury, Tasmania
Posts: 1,203
Demosaic/debayer Sony NEX OSC?

I've been using Nebulosity (Stark Labs) with success for pre-processing my monochrome CCD images captured in LRGB, but I'd like to now use it with my Sony NEX-3 DSLR (OSC). However, when I go to demosaic the RAWs, Nebulosity does not recognise the camera and so switches to manual mode. (Bah - not a Canon or Nikon! )

So I'm not sure what the best settings might be for the matrix offset and color control. The standard of X=0, Y=0 and a matrix with 1s in the diagonals and 0s in other elements gives me rather unsatisfactory results - a very greenish image. Any clues? (or perhaps you know where I can look this up -- I didn't have much success in my web search).

I do wonder what dcraw might use for debayering a Sony NEX-3. It's what I've been using previously when stacking with DeepSkyStacker (I pre-prepare the files using dcraw before loading them into DSS).
Reply With Quote
  #2  
Old 01-08-2014, 07:14 AM
multiweb's Avatar
multiweb (Marc)
ze frogginator

multiweb is offline
 
Join Date: Oct 2007
Location: Sydney
Posts: 22,060
I have a NEX-5 and I think I used PixInsight or CCD Stack to debayer. They will both read ARW files. From memory the bayer pattern is RGGB
Reply With Quote
  #3  
Old 01-08-2014, 11:15 AM
Amaranthus's Avatar
Amaranthus (Barry)
Thylacinus stargazoculus

Amaranthus is offline
 
Join Date: Jan 2014
Location: Judbury, Tasmania
Posts: 1,203
Thanks Marc, that's useful, the NEX-3 uses the same sensor as the NEX-5. I wonder if the straight 1:1:1 RBG channel is considered best for this camera?
Reply With Quote
  #4  
Old 01-08-2014, 12:42 PM
LewisM's Avatar
LewisM
Novichok test rabbit

LewisM is offline
 
Join Date: Aug 2012
Location: Somewhere in the cosmos...
Posts: 10,388
I once asked Starlight Xpress what the bayer matrix order was for the SXVR-M25C OSC CCD - I was told I had to experiment as each one was different!

I hope camera makers keep to some set standard at least. Most Sony sensors I believe tend to maintain GRBG
Reply With Quote
  #5  
Old 01-08-2014, 12:51 PM
Amaranthus's Avatar
Amaranthus (Barry)
Thylacinus stargazoculus

Amaranthus is offline
 
Join Date: Jan 2014
Location: Judbury, Tasmania
Posts: 1,203
I guess the order (RGGB or GRBG etc.) are controlled by setting either the X or Y offsets to zero or 1, right? Do you know how the 4 options specify this Bayer pattern?

RGGB: X = ?, Y = ? (is this the default, 0, 0?)
GRBG: ?
BGGR: ?
GBRG:?

Looking at the Bayer Filter Pattern that DeepSkyStacker displays for the Sony A100 it looks to be RGGB, whereas for the Sony DSC-R1 it is GRBG. I think the NEX is probably aligned with the A100, since it is part of the Alpha line. But the question of which offset specifies what still remains...

Thanks!
Reply With Quote
  #6  
Old 01-08-2014, 02:43 PM
multiweb's Avatar
multiweb (Marc)
ze frogginator

multiweb is offline
 
Join Date: Oct 2007
Location: Sydney
Posts: 22,060
Quote:
Originally Posted by Amaranthus View Post
Thanks Marc, that's useful, the NEX-3 uses the same sensor as the NEX-5. I wonder if the straight 1:1:1 RBG channel is considered best for this camera?
I usually use 0.5 for green. But you can debayer at 1:1:1 then tweak later. I don't know DSS so can't help on the debayering in it.
Reply With Quote
  #7  
Old 01-08-2014, 03:15 PM
Amaranthus's Avatar
Amaranthus (Barry)
Thylacinus stargazoculus

Amaranthus is offline
 
Join Date: Jan 2014
Location: Judbury, Tasmania
Posts: 1,203
Yep, I think I'll leave the diagonal as 1:1:1 and do the colour tweaking in post-processing.

With trial-and-error experimenting, I answered my question. The correct offset for the Sony NEX-3 was X=1, Y=1. So there you go!

I'm still not sure what Bayer pattern that corresponds too, given that I don't know what the default Nebulosity expects, but that's all rather immaterial to me now
Reply With Quote
Reply

Bookmarks

Thread Tools
Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT +10. The time is now 01:30 AM.

Powered by vBulletin Version 3.8.7 | Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
Advertisement
Testar
Advertisement
Bintel
Advertisement