Bayer Matrix for ZWO ASI224MC

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bellavia
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Bayer Matrix for ZWO ASI224MC

Post by bellavia » Mon Nov 27, 2017 2:26 am

Does anyone know the Bayer Matrix for ZWO ASI224MC?

Is it R-G-G-B?

I am getting terrible colors when I do a de-bayering of the 16-bit FITS file, using Nebulosity (latest version, 4.17).

I've tried changing the diagonal terms of the color balance matrix, but nothing works

There are two attachments:
The default is using R-G-B = 1.0 1.0 1.0, and the nebula looks yellow
I tried this, R-G-B = 0.6 0.8 1.6, and the nebula is starting to look normal at the expense of all the stars and background being much too blue.

Any help is appreciated.

Steve

P.S. Sorry if this issue has been addressed, but I did a search on the forum and surprisingly, nothing came up on this topic.
Attachments
Nebulosity_with_RGB_0p6-0p8-1p6.JPG
Nebulosity_with_RGB_1-1-1.JPG

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Sam
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Re: Bayer Matrix for ZWO ASI224MC

Post by Sam » Mon Nov 27, 2017 8:43 am

it's RGGB, but different app call it different
I think the yellow one is correct
you need to adjust the white balance to make the color better
ZWO Founder
Location:lon=120.6 lat=31.3
SuZhou China

bellavia
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Re: Bayer Matrix for ZWO ASI224MC

Post by bellavia » Mon Nov 27, 2017 8:34 pm

Sam wrote:it's RGGB, but different app call it different
I think the yellow one is correct
you need to adjust the white balance to make the color better
This is an image of a blue cable on a brown desk. When I debayer it with RGB , the cable is green.
When I use CMYG, it gets much closer.
But I cannot use CMYG for the nebula, as it creates an odd aritfact.
Attachments
Nebulosity_with_CMYG_1-1-1.JPG
blue-cable-on-brown-desk_using_CMYG.jpg
blue-cable-on-brown-desk.jpg

bellavia
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Re: Bayer Matrix for ZWO ASI224MC

Post by bellavia » Mon Nov 27, 2017 8:46 pm

bellavia wrote:
Sam wrote:it's RGGB, but different app call it different
I think the yellow one is correct
you need to adjust the white balance to make the color better
This is an image of a blue cable on a brown desk. When I debayer it with RGB , the cable is green.
When I use CMYG, it gets much closer.
But I cannot use CMYG for the nebula, as it creates an odd aritfact.

This is interesting: I opened the same file in APT's previewer.

The cable is still green, but the desk is closer to brown (yellow?)
Attachments
blue-cable-on-brown-desk_APT.jpg

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Sam
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Re: Bayer Matrix for ZWO ASI224MC

Post by Sam » Wed Nov 29, 2017 6:27 am

this is because there is no IR-CUT filter

you can add one IR-CUT filter so the final image is not so red
ZWO Founder
Location:lon=120.6 lat=31.3
SuZhou China

bellavia
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Re: Bayer Matrix for ZWO ASI224MC

Post by bellavia » Wed Nov 29, 2017 1:55 pm

Sam wrote:this is because there is no IR-CUT filter

you can add one IR-CUT filter so the final image is not so red
But the image is NOT too RED. it is too GREEN, which is the opposite of RED.

I think there is something wrong with the method the FITS header is being written OR the matrix is NOT R-G-G-B.

I was using this camera as a test to see if I would purchase a lager chip, cooled ZWO color camera.

But after this experience, I will not. It is not working out at all, and there is very little help or technical support of these products.

bellavia
Posts: 23
Joined: Mon Nov 27, 2017 2:15 am

Re: Bayer Matrix for ZWO ASI224MC

Post by bellavia » Thu Nov 30, 2017 6:41 pm

bellavia wrote:
Sam wrote:this is because there is no IR-CUT filter

you can add one IR-CUT filter so the final image is not so red
But the image is NOT too RED. it is too GREEN, which is the opposite of RED.

I think there is something wrong with the method the FITS header is being written OR the matrix is NOT R-G-G-B.

I was using this camera as a test to see if I would purchase a lager chip, cooled ZWO color camera.

But after this experience, I will not. It is not working out at all, and there is very little help or technical support of these products.
Hi again,
It took much effort, but I resolved the issue.
You need to apply an offset, as the software does not "know" which pixel to start with for the R-G-G-B mosaic.
For Nebulosity, the offset is 1,1 for X,Y
Then, after that, you can tweak further. This is not final (as I am still waiting for my photo color card to arrive), but does present fairly good colors. I will post again if I improve upon this but for now, the color balance matrix should be as follows:

0.87 0.10 0.00
0.10 0.89 0.00
0.00 0.25 1.30

These are the rows and columns for R-G-B
the columns are the input, and the rows are output
For example, row 1 above is applying 87% of the red to the red channel, 10% of green to the red channel and 0% of blue to the red channel. (This does not have to add up to 100%, nor does the determinant of this matrix need to be 1.0)

Attached is the summary of what I have done so far.

As I said, if I get it better, I'll let you know, but this is a good place to start
Attachments
ZWO ASI224MC Demosaic-ing in Nebulosity.png

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Sam
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Re: Bayer Matrix for ZWO ASI224MC

Post by Sam » Fri Dec 01, 2017 4:00 am

white balance is always need to adjust
and different software use different way

that's good news there is some improvement
ZWO Founder
Location:lon=120.6 lat=31.3
SuZhou China

bellavia
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Re: Bayer Matrix for ZWO ASI224MC

Post by bellavia » Tue Dec 05, 2017 1:26 am

Sam wrote:white balance is always need to adjust
and different software use different way

that's good news there is some improvement
I finally got my color card, and the latest settings to get better colors are extremely simple (actually embarrassing, considering what I had in my last post, as it is just the diagonal terms, and nice round numbers).
This seems to work well enough to call it a day:

Matrix offset x,y: 1,1

Color Control:

R G B
R 0.80 0.00 0.00
G 0.00 0.80 0.00
B 0.00 0.00 1.25
Attachments
ZWO_ASI224MC_color_Card_color_balance_15-resize.jpg
color_control_15.jpg

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Sam
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Re: Bayer Matrix for ZWO ASI224MC

Post by Sam » Thu Dec 07, 2017 2:15 am

thanks for sharing
ZWO Founder
Location:lon=120.6 lat=31.3
SuZhou China

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