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Hi.

Have just taken my first image with this camera,and am bitterly disapointed.My first go at OSC other than DSLR.

I am using APT for image aquisition at Unity Gain and set at RGGB.All the images are downloading as bright GREEN.Is this normal.

I use Deepsky Stacker for stacking and i set to RGGB in the set up.In photoshop i balance the colours,apply a stretch,but all the stars and Galaxies are just yellow,no variation of colours.

I must be doing something wrong here.

I enclose the final image.

Any help please.

Mick.

Autosave.png

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Hello Mick, I'm not very experienced with this, but I have a ASI533 and also get very green images coming out after DSS stacking. I then do photometric colour calibration using SIRIL and it all g

Very quick processing in Gimp gave me this (mind you - I did not touch color balance nor pushed saturation - just a simple luminance stretch - will give you steps to reproduce this if you like):

As Martin says, green is definitely normal.  Here's a couple of examples - different scopes, same camera (533).  I don't know if there's such a thing as too green or problem green - how do yours look?

Posted Images

55 minutes ago, astro mick said:

am using APT for image aquisition at Unity Gain and set at RGGB.All the images are downloading as bright GREEN.Is this normal.

With my  ZWO OSC, the images appear as BW in APT.

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Yes they do come out green, this is normal.

In DSS you can reduce the green cast on the stacked image.

In the Options menu > Settings > Stacking Settings >Light Tab > RGB Channels Background Calibration > Select "RGB Channels Background Calibration" so there's a tick by it > Click  "Options" below this and set to Calibration Method = Rational & RGB Background Calibration method = Minimum.

Now restack and the green cast should have gone in the final image.

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5 hours ago, astro mick said:

.All the images are downloading as bright GREEN.Is this normal.

As Martin says, green is definitely normal.  Here's a couple of examples - different scopes, same camera (533).  I don't know if there's such a thing as too green or problem green - how do yours look?

image.png.2f043600efd60b9e72cd46caee791bc6.png

image.png.c3c10d03ce8dfe62aae9ef0649fd4919.png

4 hours ago, tooth_dr said:

With my  ZWO OSC, the images appear as BW in APT.

Are they debayered Adam?  This setting will do that:

image.png.d392a0b9ae773ae3814d080b506d2280.png

If I'm using Apt, I tend to adjust the Red and Blue Channel Scaling Factor to offset the green (and sometimes the Auto-Stretch Factor too).  They are in the same tab, right hand side:

image.png.9a8d21d173fa31f5be7f1a1703814d77.png

Here's one of the above with the scaling settings (the other one would need higher values!):

image.png.ba096972f1d836b715fa751e48f2c169.png

Edited by geeklee
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1 hour ago, Budgie1 said:

Yes they do come out green, this is normal.

In DSS you can reduce the green cast on the stacked image.

In the Options menu > Settings > Stacking Settings >Light Tab > RGB Channels Background Calibration > Select "RGB Channels Background Calibration" so there's a tick by it > Click  "Options" below this and set to Calibration Method = Rational & RGB Background Calibration method = Minimum.

Now restack and the green cast should have gone in the final image.

Thanks for this Martin.

Mick.

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Hi.

I still can get no colour out of this camera.

I have set all the parameters in DSS,but still all i get is grey(see attached image.)Set thr debayer to RGGB

I just dont understand what is going on.I,m on th verge of returning this camera.

Their is not a hint of red in M82 

Can someone  who uses this DSS software help.

I have set the parameters in APT to comply with Geeklees asvice above,but still grey.The image does,nt come out Green though.

Mick.

M81.png

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1 hour ago, astro mick said:

I have set the parameters in APT to comply with Geeklees asvice above,but still grey.The image does,nt come out Green though.

HI Mick - I don't see the above as grey, just green.  With the green removed, I see mainly brown and red.  I've stretched it a little more so I could look at the colour - great detail in there BTW

image.png.d470d27c60be5546609f5650aac63090.png

In Apt, those scaling settings are just for preview purposes, they have no bearing on the image output at the end or what you'll be working with to integrate.

I'm not sure if DSS is causing an issue, sorry.  Hopefully some perseverance will get you the result you're after. 

For what it's worth, if I try and mess about with the background or the colour calibration on the compressed non-linear image above it doesn't go well.  Did you try these steps when the data was non-linear?

Edited by geeklee
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I think the only settings you need to look out for in DSS is the RAW/FITS DDP Settings in the menu. This is what I have those set too for my ASI294MC and notice these are on the FITS Tab:

DSS-FITS.png.1d00e274ebf745082750f0a6103e57c5.png

Also, here are the stacking settings and RGB Background Calibration I use. Note that I use Kappa-Sigma Clipping to remove any satellite trails but this won't effect the colour of the image. ;) 

DSS-Stack.png.9398ab159e20440a9feec6c21bf60015.png  DSS-Background.png.f9b06048d8c2c3a35e4da31cfb7a163d.png

It may be handy if posted your stacked image from DSS so we can try processing it and see what we can find.

Don't give up hope on it yet, I had the same issue when I got the 294MC and in my case it was the lack of a tick in the FITS Files tab in my first image above. ;)

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22 hours ago, Budgie1 said:

I think the only settings you need to look out for in DSS is the RAW/FITS DDP Settings in the menu. This is what I have those set too for my ASI294MC and notice these are on the FITS Tab:

DSS-FITS.png.1d00e274ebf745082750f0a6103e57c5.png

Also, here are the stacking settings and RGB Background Calibration I use. Note that I use Kappa-Sigma Clipping to remove any satellite trails but this won't effect the colour of the image. ;) 

DSS-Stack.png.9398ab159e20440a9feec6c21bf60015.png  DSS-Background.png.f9b06048d8c2c3a35e4da31cfb7a163d.png

It may be handy if posted your stacked image from DSS so we can try processing it and see what we can find.

Don't give up hope on it yet, I had the same issue when I got the 294MC and in my case it was the lack of a tick in the FITS Files tab in my first image above. ;)

Hi Martin.

Thanks for all this.I have managed to pull some colour out of it as in my image below.

I enclose a stacked 16bit file straight from DSS in Tiff format.

Mick.

 

M81a.tif

M81-82.png

Edited by astro mick
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This is a strange one (for me anyway) because there is colour in there, just not very much.

I split the image into RGB channels in PixInsight and I can see the difference between them, although it's very subtle. I would have expected to see more detail in the R channel and more noise + less detail in the G & B channels, but that's not the case. The B channel is the most obvious in its difference to the others with more detail showing in the arms of M81 and the centre of M82. 

But combined the colour just isn't there for some reason. I even tried to increase the saturation on the stars, which normally brings out blue & orange halos, but it hasn't.

I'm at the end of my experience & suggestions, other than to check the DSS settings again as I'm sure this is a settings issue. Maybe drop @vlaiv a PM and ask if he has any suggestions?

This is what I managed to get on a quick process in PixInsight last night.

M81a.thumb.png.37bea3bd52eac8274d4f6d4112a890e2.png

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17 hours ago, astro mick said:

I enclose a stacked 16bit file straight from DSS in Tiff format.

Very quick processing in Gimp gave me this (mind you - I did not touch color balance nor pushed saturation - just a simple luminance stretch - will give you steps to reproduce this if you like):

image.png.c0f63ccc79fbd0222a975c696b51244b.png

DSS background calibration can skew color in the image. It is needed for kappa sigma clip (algorithm requires normalized frames).

Maybe best approach would be to use simple average stacking and no background calibration - just to see what sort of color information is there.

Issue with astro cameras is that they don't have color correction matrix embedded in them like DSLR cameras do. We get raw color from them and that color needs to be adjusted in order to be accurate.

I can talk about this process, but I must warn you that there are people that insist that what I'm saying is wrong and that there is no "proper color" for astronomical images.

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16 minutes ago, vlaiv said:

I must warn you that there are people that insist that what I'm saying is wrong and that there is no "proper color" for astronomical images.

Well its sure nice to have the knowledge to make them how each one of us thinks they should be.. I mean the Hubble guys did..,

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31 minutes ago, jetstream said:

Well its sure nice to have the knowledge to make them how each one of us thinks they should be.. I mean the Hubble guys did..,

Well, I think that in the end it comes down to what we mean when we say color.

I know - its strange, color is color, right?

Well, it turns out that there are different meanings to the word color. I'll use another word to explain this - temperature.

We use term temperature to express physical property of some object. We can measure it with a device and we assign numerical value to it. We can say - water in this bowl is 8°C.

Then there is temperature that we feel. We can be warm or cold, or just right. In fact we have whole spectrum of words that we use to describe how we "feel", or what the temperature of the object "feels" like.

However, there is difference between the two. Objective temperature is something many people can measure but we all will agree on measured value given certain standard of measurement to follow (units in which we measure, way we measure and so on). Subjective temperature is personal feel and two people judging same temperature can give contradictory answers - and neither of them needs be wrong.

Imagine above bowl of water at 8°C - in hot summer day in Caribbean. You wear nothing but swimming shorts and it is rather hot outside. You put your hand in that bowl of water and you say with confidence:

"This water is pleasantly chilly".

Take same bowl of water at same temperature in wintertime in your back yard. You've been observing at your telescope lightly clothed (however this is unlikely in real life) for couple of hours and you are starting to treble from cold. Now you place your same hand in that same water and conclude that temperature is now "Comfortably warm".

How can that be? Well - that is subjective feel.

Similar thing happens with colors - our perception of the color changes with conditions and it is relatively hard to simulate "feel" of a color in different conditions. Color appearance models try to do that and when we talk about white balance - it is actually part of our perception and not color processing of sensor data. That is why there is no white balance in astrophotography. We are not attempting to recreate the "feeling" - but rather to record and synthesize equivalent spectrum.

That part we can do without ambiguity - in the same way people are able to measure temperature and all agree on what the value of measurement is. They can even produce water that is exactly 8°C in temperature and different people sensing that water will have different "feel" - but it will be the same temperature.

Color reproduction and matching has nothing to do with our perception. Color appearance has - but that is something completely different.

I think that as a first step - it is important that we know how to accurately record and reproduce color. Only then we can deal with color appearance if we wish to do so.

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10 hours ago, astro mick said:

Hi Guys.

I appreciate all your imput,but have binned it,cant be doing with all this trying to sort things.

Back to my trusty 314L+ and filters.

Never fails.

But again thanks.

Mick.

Mick is it worth finding someone that has taken same image using same camera at same unity settings and comparing Raw file just to see how they compare just incase there is something way off with your camera.

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4 hours ago, astro mick said:

Hi.

Perhaps it is,but just have no love for this camera,or indeed cmos.

Its a shame that the traditional ccd cameras are still rather expensive.

Mick. 

Did you post a single sub Mick in the thread?  I get more colour from my single CMOS subs than your stack, and my Atik CCD cant touch the CMOS for noise control. 

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27 minutes ago, tooth_dr said:

Did you post a single sub Mick in the thread?  I get more colour from my single CMOS subs than your stack, and my Atik CCD cant touch the CMOS for noise control. 

Part of the color problem has to do with the way data is stretched.

That is particularly present with CMOS sensors, as CMOS sensors enable shorter exposures so signal is particularly faint in such recordings and needs to be stretched more strongly.

"Regular" stretching simply desaturates colors - because we use non linear transform and RGB ratio is not preserved.

Instead - one should preserve RGB ratio and stretch only luminance / intensity of light to preserve color.

 

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3 hours ago, tooth_dr said:

Did you post a single sub Mick in the thread?  I get more colour from my single CMOS subs than your stack, and my Atik CCD cant touch the CMOS for noise control. 

No Not a single one.

Anyway its back with the dealer,and i,m nearly a grand better off🤗

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13 hours ago, bottletopburly said:

Mick is it worth finding someone that has taken same image using same camera at same unity settings and comparing Raw file just to see how they compare just incase there is something way off with your camera.

@astro mick @bottletopburly  Here's an old 120s sub using an 80mm refractor with my 533MC Pro, unity gain (100) and -10degC.  Preview below is the debayered single frame with STF then with unlinked STF.  Third image is stack of ~2.5 hours - again just an STF. FITS file of the single sub attached at bottom.

image.thumb.png.57aa998e9daca2ea4592ed703e670317.png

image.png.a95496ea98962cbbc6c46e63b7d16c1c.png

Here's what I managed with the stack at the time (to show colour):

https://www.astrobin.com/mcl0r7/?nc=user

L_2020-03-10_22-30-09_Bin1x1_120s__-10C.fit

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1 minute ago, astro mick said:

No Not a single one.

Anyway its back with the dealer,and i,m nearly a grand better off🤗

Ah... this was just posted as I'd added my images - d'oh!  Apologies I had to look them out so it took a little bit.

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Interesting to see the difference between the sensors on these cameras.

This is one of M81 & M82 I took back in January using the ASI294MC Pro at -10°C and unity gain (120). This is a single sub debayered and with STF, then with Background Neutralisation & Colour calibration.

Below that is the stack of about 65 x 180s subs with darks, flats & dark flats. Stacked in DSS and processed in PI.

M81-single.thumb.png.10f210b6564b79a75292fb880b266600.png

M81-M82-31012021.png.269b525003b8f60f9d7f59fbefefad56.png

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Hello Mick,

I'm not very experienced with this, but I have a ASI533 and also get very green images coming out after DSS stacking. I then do photometric colour calibration using SIRIL and it all goes away and I get nice colours.

Tedbert

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On 07/05/2021 at 17:15, tedbert said:

Hello Mick,

I'm not very experienced with this, but I have a ASI533 and also get very green images coming out after DSS stacking. I then do photometric colour calibration using SIRIL and it all goes away and I get nice colours.

Tedbert

Hi Tedbert.

I,m glad its worked out for you.I have proberbly been impatient and not willing to learn the correct process.

Mick.(Dont know what SIRIL is?

 

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