Debayerization needed

[Nocturnal]

You'd have to ask Luc how DSS really works but I'm pretty sure pixel rejection happens before debayering. I've had mixed results with the hot pixel removal so I now do it before feeding the raw images to DSS.

[ManoloL]

Hola:

Para intentar resolver estos problemas esta el Dithering, dentro de las técnicas a aplicar en la captura de imagenes.

Hi:
To try to solve these problems is the Dithering within the techniques to be applied to the adquiring images.

[Nocturnal]

Yes but only with a rejection stacking algorithm.

[ManoloL]

Yes but only with a rejection stacking algorithm.

Hi:

Of course

Best regards

[vicent_peris]

I can't how you can do sigma rejection before debayerizing the image set, as you need a set of pixels at position p. This means that you must register all the image set.

Any ideas??



Vicent.[/i]

[Nocturnal]

You are right Vicent that this can't be done before debayering. However sigma clip would still help get rid of hot pixels in that case if they are spread out due to dithering. Of course the averaging part of the debayering process smears out the pixel so the process isn't perfect. It's one of the reasons I prefer to remove the hot/cold pixels in my raw images before debayering. I still dither though.

[Niall Saunders]

There is a problem with DSS, I believe, in that it does NOT correctly deBayer Meade DSI OSC (CMYG) RAW images.

I hope to demonstrate this, and why, but I do not yet have 'proof positive' and I do NOT want to disparage DSS in ANY way whatsoever.

What I 'do' want to be able to demonstrate is HOW a DSI image SHOULD be deBayered. Thereafter, if my method does prove to be different from others, and if it shows a worthwhile improvement, I am hoping that anyone who offers a Meade DSI deBayering algorithm will be able to make use of my results - FOC, bar from mention.

Cheers, and back to the script . . . . .

[Astrocava]

Hola:

Para intentar resolver estos problemas esta el Dithering, dentro de las técnicas a aplicar en la captura de imagenes.

Hi:
To try to solve these problems is the Dithering within the techniques to be applied to the adquiring images.

Of course :-), but I have problems with guiding and imaging with same program.

I can't how you can do sigma rejection before debayerizing the image set, as you need a set of pixels at position p. This means that you must register all the image set.

Any ideas??



Vicent.[/i]

I'm thinking about it, but no idea.  :evil:

It's one of the reasons I prefer to remove the hot/cold pixels in my raw images before debayering. I still dither though.

How do you do this? with a hot pixel map? what happens with the "holes"?

Sergio

[Nocturnal]

Yes, with a hot pixel map. Various software can do this but I wrote my own utility.

http://www.tungstentech.com/Software/FixFITS/tabid/78/Default.aspx

I know Juan would like me to have written that in PCL but frankly I wanted something that I could share with others even if they didn't have PI.

Anyway, the hot/cold pixels are detected in a dark frame by calculating the stddev and then comparing pixel values to the mean +/- sigma*stddev. For an OSC frame each hot/cold pixel is replaced by the average of its neighbors two pixels away. For a mono frame the immediate neighbors are used. Simple.

Now that I've started dabbling in PCL I may turn this into a PI module but there is so much code required just to deal with parameters and GUI that it's a bit daunting.

[Astrocava]

Thanks (a bit late), Sander. I know the hot pixel map from astroart.   Will check what  DSS do with the hot pixel options. Only the random hot pixels left...

Sergio