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Effective resolution - OSC vs mono


StuartT

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I've just bought by first mono camera (which I plan to use for solar) - the Player One Apollo M mini.

Can I just check my understanding that due to the Bayer matrix on a OSC the 'effective' resolution is lower than for a mono camera (all other things being equal)?

Thanks 

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13 minutes ago, StuartT said:

Can I just check my understanding that due to the Bayer matrix on a OSC the 'effective' resolution is lower than for a mono camera (all other things being equal)?

Yes.

OSC effectively samples at half the sampling rate of equivalent mono sensor.

5 minutes ago, scotty38 said:

No doubt Vlaiv will put you right (and me of course) but I "think" that due to debayering and then interpolation that the resolution ends up about the same. Like I said I think it's something like that.....

You can interpolate the data to get the same pixel count / image size as mono - but you can't interpolate detail.

What you can do is use Bayer drizzle (if properly implemented). That will give you almost identical resolution as mono version.

I usually advocate against use of regular drizzle - but Bayer drizzle works (this is because pixels are indeed smaller - only "sparsely" distributed in Bayer matrix).

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Thanks @vlaiv Much appreciated.

1 minute ago, vlaiv said:

What you can do is use Bayer drizzle (if properly implemented). That will give you almost identical resolution as mono version.

I usually advocate against use of regular drizzle - but Bayer drizzle works (this is because pixels are indeed smaller - only "sparsely" distributed in Bayer matrix).

Is Bayer drizzle something you do in processing or capture?

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You can split the sub into its 4 base components: 1 red 2 green and 1 blue monochrome subs without debayering. Then you see that each of the mono subs are now only 1/4 the resolution or sampled at half the rate compared to the resolution advertised. This is the real resolution captured by the camera and no interpolation takes place during debayering (because it is not debayered).

Not sure i would recommend doing this, but if you're bored you can play with this idea and process OSC as you would mono. The downside of course is extra faff during preprocessing and you get 4x the amount of subs to stack as a result.

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1 minute ago, StuartT said:

Thanks @vlaiv Much appreciated.

Is Bayer drizzle something you do in processing or capture?

It is part of the stacking - or rather special way you stack the data.

Bayer matrix is left as is, and then aligned with main stack. Pixels are then stacked against color rather than against each other. After frame is aligned - if pixel is R pixel - it gets stacked to R channel of the image, if it is blue pixel - it gets stacked against B channel and if it is green pixel - it gets stacked against green channel.

Deep sky stacker supports this stacking mode. AutoStakkert!3 (planetary stacking) - by default handles OSC data like that.

Not sure about other stacking software.

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1 minute ago, ONIKKINEN said:

You can split the sub into its 4 base components: 1 red 2 green and 1 blue monochrome subs without debayering. Then you see that each of the mono subs are now only 1/4 the resolution or sampled at half the rate compared to the resolution advertised. This is the real resolution captured by the camera and no interpolation takes place during debayering (because it is not debayered).

Not sure i would recommend doing this, but if you're bored you can play with this idea and process OSC as you would mono. The downside of course is extra faff during preprocessing and you get 4x the amount of subs to stack as a result.

That is how I process OSC data "by default". Split channels without debayering and stack each as if is mono.

Green gets x2 number of subs "boost" over blue and red that way (which is x1.41 SNR improvement).

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err.. ok. I don't understand any of that, I'm afraid. I've never processed mono data before (or even collected any!).

My OSC data I process with Siril, but I just use existing scripts so I am not really sure what it's doing 'under the hood'

Anyway. No worries. I have an answer to my original question. Thanks

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Just now, vlaiv said:

That is how I process OSC data "by default". Split channels without debayering and stack each as if is mono.

Green gets x2 number of subs "boost" over blue and red that way (which is x1.41 SNR improvement).

I have played around with this as well. I have a script in Siril that calibrates my frames and outputs split mono frames in the end, only thing i need to do is to put the frames in their folders in the working directory (i use symbolic links so no copying). Siril does this really fast and its only a minor nuisance now that im used to it.

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2 hours ago, StuartT said:

I've just bought by first mono camera (which I plan to use for solar) - the Player One Apollo M mini.

Can I just check my understanding that due to the Bayer matrix on a OSC the 'effective' resolution is lower than for a mono camera (all other things being equal)?

Thanks 

Oooh a player 1 guinea pig ... let us know how you get on... looks like a interesting camera 

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9 hours ago, vlaiv said:

That is how I process OSC data "by default". Split channels without debayering and stack each as if is mono.

Green gets x2 number of subs "boost" over blue and red that way (which is x1.41 SNR improvement).

More than that as the QE of the camera can be significantly more in the Green than Blue or even Red.

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14 minutes ago, Adam J said:

More than that as the QE of the camera can be significantly more in the Green than Blue or even Red.

That is actually quite good thing - if one takes advantage of that.

Human eye/brain system is most sensitive to noise and detail in green part of spectrum (Y component of XYZ color space).

Green in OSC cameras is very close match to Y component.

Best processing for this case is to create OSC RAW -> XYZ color space conversion matrix and then process Y as luminance and use X and Z as color information.

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1 hour ago, PadrePeace said:

Can APP do that OSC stacking drizzle thing Vlaiv / AdamJ?

Its essential to dither every frame if you are going to use drizzle. That can be expensive in terms of time and the SNR will be decreased if bayer drizzle is used.

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1 hour ago, vlaiv said:

That is actually quite good thing - if one takes advantage of that.

Human eye/brain system is most sensitive to noise and detail in green part of spectrum (Y component of XYZ color space).

Green in OSC cameras is very close match to Y component.

Best processing for this case is to create OSC RAW -> XYZ color space conversion matrix and then process Y as luminance and use X and Z as color information.

Also hence why debayering algorythems tend to weight the green channel (as a relative measure) when interpolating the luminance of each colour channel. But that may be what you are trying to say above.

 

Edited by Adam J
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