Page 1 of 2

Bayer Matrix for ZWO ASI224MC

Posted: Mon Nov 27, 2017 2:26 am
by bellavia
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.

Re: Bayer Matrix for ZWO ASI224MC

Posted: Mon Nov 27, 2017 8:43 am
by Sam
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

Re: Bayer Matrix for ZWO ASI224MC

Posted: Mon Nov 27, 2017 8:34 pm
by bellavia
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.

Re: Bayer Matrix for ZWO ASI224MC

Posted: Mon Nov 27, 2017 8:46 pm
by bellavia
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?)

Re: Bayer Matrix for ZWO ASI224MC

Posted: Wed Nov 29, 2017 6:27 am
by Sam
this is because there is no IR-CUT filter

you can add one IR-CUT filter so the final image is not so red

Re: Bayer Matrix for ZWO ASI224MC

Posted: Wed Nov 29, 2017 1:55 pm
by bellavia
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.

Re: Bayer Matrix for ZWO ASI224MC

Posted: Thu Nov 30, 2017 6:41 pm
by bellavia
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

Re: Bayer Matrix for ZWO ASI224MC

Posted: Fri Dec 01, 2017 4:00 am
by Sam
white balance is always need to adjust
and different software use different way

that's good news there is some improvement

Re: Bayer Matrix for ZWO ASI224MC

Posted: Tue Dec 05, 2017 1:26 am
by bellavia
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

Re: Bayer Matrix for ZWO ASI224MC

Posted: Thu Dec 07, 2017 2:15 am
by Sam
thanks for sharing