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Old 31-07-2014, 11:36 PM
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Amaranthus (Barry)
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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).
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Old 01-08-2014, 07:14 AM
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multiweb (Marc)
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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
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Old 01-08-2014, 11:15 AM
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Amaranthus (Barry)
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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?
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Old 01-08-2014, 12:42 PM
LewisM
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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
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Old 01-08-2014, 12:51 PM
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Amaranthus (Barry)
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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!
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Old 01-08-2014, 02:43 PM
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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.
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Old 01-08-2014, 03:15 PM
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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
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