My Eclipse Frames - R/B Balance

[DamienCannane]

Good evening,

I hope that all of you who were trying got to see the eclipse today. It was incredible!

I used my ASI2600MC Pro for image capture, utilizing Sharpcap Pro's Sequencer to automate the whole thing. That worked flawlessly, except I made a bone-headed mistake. During the partial phases, I was pre-adjusting the color balance 45 for R, 50 for B to compensate for the strong red bias in my solar filter...and I thought I had edited the script to return it to 50 and 50 for the totality sequence, but I guess not.

When I debayer the FITS files, they all show up with either green or purple as the overall color cast, rather than a nice white (depending on what debayer algorithm I use). What's the best way to correct for this? Please tell me there's a good way to do it...I've got many of the common astronomy and non-astronomy software options available to me.


Thank you in advance!

Damien

Here's my capture settings:

[ZWO ASI2600MC Pro]
CameraSerialNumber=1422010509020900, via USB3
FrameType=Light
Debayer Preview=On
Pan=0
Tilt=0
Output Format=FITS files (*.fits)
Binning=1
Capture Area=6248x4176
Colour Space=RAW16
Exposure/Gain Shift=0
Hardware Binning=Off
High Speed Mode=On
Turbo USB=50
Flip=Vert
Frame Rate Limit=4 fps
Gain=100
Exposure=166.6670ms
Timestamp Frames=Off
White Bal (B)=50
White Bal (R)=45
Brightness=50
Window Heater Power=Off
Cooler Power=0
Temperature=34.2
Target Temperature=30
Cooler=Off
Auto Exp Max Gain=350
Auto Exp Max Exp MS=30000
Auto Exp Target Brightness=100
Mono Bin=Off
Fan Speed Adjust=255
Power Led Bright=255
Usb Hub Reset=On
CA Reduction/Synthetic Blue=Off
Mask over exposed pixels=Off
Flip (after dark/flat)=None
Trail Width=3
Minimum Trail Length=100
Trail Detection Sensitivity=9
Remove Satellite Trails=Off
Background Subtraction=Off
Planet/Disk Stabilization=Off
Banding Threshold=10
Banding Suppression=0
Apply Flat=None
Hot Pixel Sensitivity=5
Subtract Dark=None
DisplayStretchEnable=0
NegativeDisplay=0
Display Black Point=0.00732421875
Display MidTone Point=0.11767691918006949
Display White Point=0.999755859375
Notes=
TimeStamp=2024-04-08T18:58:40.6610608Z
SharpCapVersion=4.1.11974.0
StartCapture=2024-04-08T18:58:40.5712606Z
MidCapture=2024-04-08T18:58:41.4477208Z
EndCapture=2024-04-08T18:58:42.3241810Z
JDStartCapture=2460409.290747
JDMidCapture=2460409.290757
JDEndCapture=2460409.290768
Duration=1.753s
FrameCount=7
ActualFrameRate=3.9933fps
TimeZone=-5.00

[admin]

Hi,

seeing a purple colour cast in a debayered image is usually a sign of having the wrong pattern selected - green is much more usual with modern cameras as the green pixels on the sensor are more sensitive, so record a stronger signal. I wouldn't have thought that the 45/50 colour balance settings would make enough difference to really throw things very far off, so you may just be getting the natural green tint that comes from the camera.

It might be worth you sharing a single still frame here for us to check - I did notice in your capture settings that you had a display stretch enabled, so the saved image may be darker than the ones you were seeing on screen.

One quick way to re-balance the colours may be to use the 'PIPP' tool (Planetary Imaging Pre-Processor). This can process various file types in bulk, and one of the options on the 'Processing Options' is histogram equalization, where you can ask it to equalize the channels individually - I think this should basically white balance the input data.

Unfortunately the original PIPP website has vanished, but you can still find details and download the installers here : https://web.archive.org/web/20230531163 ... /downloads

cheers,

Robin