Image coloring not correct

[Jsorace04]

Now that I have everything working the way I'd like, I still am struggling to get the correct coloring from my images. During the day my sky is almost black like it would look when a storm comes through. And my clouds at night look green.

Suggestions are appreciated.

[EricClaeys]

@Jsorace04, Allsky allows you to set separate white balances during daytime and nighttime, although the defaults work fairly well.

What camera are you using? Does it have an Infra Red (IR) filter? Without one you'll get different colors.
Please post a daytime and a nighttime image.

[Jsorace04]

Here's an image from tonight with clouds.

Here's an image on a clear night.

Here is an image during the day.

I believe the lens that came with my ZWO asi662mc has a IR cut filter on it. I'll double check if it does but if not I do have one in my drawer

[Jsorace04]

Ok looks like auto white balance was not turned on for Nighttime photos. Now it's looks normal.

Auto white balance for daytime is enabled as well but still produces the dark sky.

[EricClaeys]

Green clouds at night could be from the lights that produce light pollution.

Your Milky Way shot looks pretty normal to me. The green on the left side could be from the same lights as the cloud picture.

If your daytime images are too dark, make sure Auto Exposure is enabled, then adjust the Mean Target as desired. You can also adjust where the Auto Exposure algorithm looks to determine how bright an image is. The area is called the "Histogram Box" and by default is 500px by 500px centered on the middle of the image. With my camera, the Sun goes through the box with throws off the exposure, so I moved the box so the Sun doesn't go through it.
To do so, in the "Image Overlay Settings" section, make sure the Overlay Method is "legacy" and Show Histogram Box is enabled. After you see where the box is, adjust the size and location via the Histogram Box setting.

[NiteRide]

This will not cover ZWO users, but for others searching discussions using Pi HQ camera:
I found (for the Pi HQ camera), choosing to apply the "scientific" tuning file during the night improved the auto-white balance colors for me. (eg removing most green tinge from city-lit clouds) on bookworm the path is: /usr/share/libcamera/ipa/rpi/vc4/imx477_scientific.json

[EricClaeys]

@NiteRide, thanks for the tip.
If you add --metadata /tmp/libcamera.json to the EXTRA_PARAMETERS setting, you can look in /tmp/libcamera.json to see what the Red and Green white balance number were. It would be interesting to compare those to what you get when not using the scientific tuning file.

[NiteRide]

with /usr/share/libcamera/ipa/rpi/vc4/imx477_scientific.json
libcamera.json

{
    "ExposureTime": 6857885,
    "AnalogueGain": 1.000000,
    "SensorTimestamp": 794463224000,
    "ScalerCrop": "(0, 0)/4056x3040",
    "ScalerCrops": "[ (0, 0)/4056x3040 ]",
    "ColourCorrectionMatrix": [ 2.038055, -1.030521, -0.019345, -0.288437, 1.700063, -0.420436, 0.046222, -0.849475, 1.795477 ],
    "FocusFoM": 2663,
    "ColourTemperature": 4000,
    "ColourGains": [ 2.934811, 1.714591 ],
    "DigitalGain": 1.000010,
    "AeLocked": false,
    "SensorTemperature": 15.000000,
    "Lux": 0.788190,
    "FrameDuration": 6858514,
    "SensorBlackLevels": [ 4096, 4096, 4096, 4096 ]
}

without
libcamera.json

{
    "ExposureTime": 4999942,
    "AnalogueGain": 4.995122,
    "SensorTimestamp": 1015714253000,
    "ScalerCrop": "(0, 0)/4056x3040",
    "ScalerCrops": "[ (0, 0)/4056x3040 ]",
    "ColourCorrectionMatrix": [ 2.255835, -1.054460, -0.201370, -0.463425, 2.165888, -0.702463, -0.143406, -0.727393, 1.870800 ],
    "FocusFoM": 5502,
    "ColourTemperature": 4000,
    "ColourGains": [ 2.510905, 1.656681 ],
    "DigitalGain": 1.000988,
    "AeLocked": false,
    "SensorTemperature": 15.000000,
    "Lux": 0.428350,
    "FrameDuration": 5000571,
    "SensorBlackLevels": [ 4096, 4096, 4096, 4096 ]
}

looks like a difference. i have the default red at 2.55 and blue at 2.0 with auto white balance on. for a few days I tried without auto white balance, but decided to see what happens with it enabled.

the above is not a perfect comparison obviously but pretty close to the same time. sliding though the blue hour towards dark, but not much clouds (yet) tonight, just a bright slice of moon and not totally dark enough for the city lights to be bouncing back down off the clouds...

[NiteRide]

oh. actually here is some sort of before and after comparison
about a month ago clip from timelapse (all default settings, no tuning file):

to compare with a snippit of cloudy images from last night when we had the scientific tuning file in play.
not perfectly white or anything, but not green, and I prefer this to the eerie green with the defaults above.

anyone else's mileage with this may vary as light pollution is going to be different wherever you are.

[Jsorace04]

Well I wasn't able to get my color right in time for the storm however the camera served it's purpose to get me outside!

[EricClaeys]

Nice aurora.