Debayering

[AndreaLiga]

Hi everyone,

I've been trying to take trial photos with my Sony a6000 with Sharp cap and ASCOM Drivers.

The resulting photos have a green tint to them and this is expected.

Sharpcap is shooting in RAW16 mode and the Bayer matrix is RGGB (according to Sony Specs).

What software can I use to debayer and get the proper colors?

Thanks in advance

 

[scotty38]

Lots of software out there from free to costly from not as complex to a bit more complex.

Free - DSS, Siril

Not expensive - Affinity Photo, Startools

More Expensive APP, PIxInsight

Plus probably loads of others too

[ONIKKINEN]

Everything is working as intended when the image comes out as primarily green. This is because you have 2 green pixels for every red and blue pixel so really it would be weird if the image is not green.

Are you trying to process a single image or what is the goal here?

Edited July 28, 2022 by ONIKKINEN

[AndreaLiga]

19 minutes ago, ONIKKINEN said:

Are you trying to process a single image or what is the goal here?

Ho Onikkinen,

I'm just playing around to get the hang of it. Yes the image comes out green and yes I'm aware that that's the way it should be.

I'm trying to process a single image to grab the mechanism.

 

Thanks

[alacant]

1 hour ago, AndreaLiga said:

What software can I use to debayer

Hi

If you're seeing colours of any sort, then the image has already been processed, Probably by the software upon which it is being displayed.

An image which has not been debayered displays a monochrome grid pattern.

Post -a link to- your raw file if you like.

Cheers

[AstroMuni]

1 hour ago, AndreaLiga said:

What software can I use to debayer and get the proper colors?

Scotty38 has answered your question 🙂 Once you have chosen something which you like post your specific queries in this forum and folk will be able to help. Good luck.

[ONIKKINEN]

5 hours ago, AndreaLiga said:

Ho Onikkinen,

I'm just playing around to get the hang of it. Yes the image comes out green and yes I'm aware that that's the way it should be.

I'm trying to process a single image to grab the mechanism.

 

Thanks

Ah, i see. Give https://siril.org/  a try then, its free and sort of easy to understand for beginners. When opening a file you can choose to not debayer the image, in which case you would be shown a monochrome image with a checkerboard pattern over it like Alacant described above. Clicking the debayer option when opening a raw file will most of the time result in the green image you had already seen.

Normally colour calibration is done after you have stacked all of your images but you can do it for just one file too. Give the tutorials a patient look while using the software for the first time as its easy to feel lost when using a piece of astronomy processing software for the first time.

[SoftwareDeveloper]

Debayering is not a single thing, there are a good list of ways to do it. Check with the wikipedia on the subject (https://en.wikipedia.org/wiki/Bayer_filter#Demosaicing). The fastest algorithm is not great for astronomy (nearest neighbor). I cant recommend a specific program, but look for one that supports choices in the algorithms used. A downside of better algorithms is they are usually noticeably slow.

Where you will find issues with debayering is when you zoom in on a star and you get "colors" that are not really there. Your noticing a green cast should not happen, that is a sign that something is wrong, even when using fast/simple approaches.

Making three exposures through three bandpass filters avoids the issue completely, and allows a monochrome camera to be used which is about 4x more sensitive to light when no filter is employed. This is why many astrophoto enthusiasts use filter wheels. Personally I own color astronomy cameras, but prefer monochrome/filter wheels. The downside of filterwheels is image registration and processing into an normal color image. Another advantage of the three filter method is an RGB image can be made from narrow band filters using specific emission lines mapped to the color planes. Very impressive looking images can be created this way, but its not a "natural color" image at that point.

Combining bandpass filters with a camera having a bayer filter grid, usually creates a mess and takes much longer exposures to get less satisfying results. Interpreting the results in any metric sense is shot in the process, as the bandpass for the individual RGB filters in the bayer array are usually not calibrated.

Certainly good results for "natural color" images can be obtained with either approach. Pick one and you will end up making great photos if you stick with it.

:)