Eclipse image- bringing out color in solar flares

J

jnatale

Member
I took this eclipse image during totality, and am having trouble bringing out any color in the solar flares or anywhere else in the image. It appears to be strictly black and white. I have included links to the raw FITS file, my finished image in Pixinsight and the Sharpcap capture file below. Any assistance processing this would be appreciated!

2024-04-08-1928_4-Sun_00001.fits

drive.google.com drive.google.com

2024-04-08-1928_4-Sun_00001.jpg

drive.google.com drive.google.com



[ZWO ASI294MC Pro (0A21820F28000900, via USB3)]
FrameType=Light
Debayer Preview=On
Pan=0
Tilt=0
Output Format=FITS files (*.fits)
Binning=1
Capture Area=4144x2822
Colour Space=RAW16
Exposure/Gain Shift=0
High Speed Mode=Off
Turbo USB=40
Flip=None
Frame Rate Limit=Maximum
Gain=50
Exposure=1.000s
Timestamp Frames=Off
White Bal (B)=76
White Bal (R)=60
Brightness=27
Cooler Power=0
Temperature=17.6
Target Temperature=-10
Cooler=Off
Auto Exp Max Gain=0
Auto Exp Max Exp MS=30000
Auto Exp Target Brightness=100
Mono Bin=Off
Power Led Bright=0
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=1
NegativeDisplay=0
Display Black Point=0.029082774049217
Display MidTone Point=0.059955724801825545
Display White Point=1
Notes=
EQMOD ASCOM HEQ5/6=RA=01:05:12,Dec=+01:17:49 (JNOW)
TimeStamp=2024-04-08T19:28:28.6409678Z
SharpCapVersion=4.1.11388.0
StartCapture=2024-04-08T19:28:27.7441296Z
MidCapture=2024-04-08T19:28:28.2441296Z
EndCapture=2024-04-08T19:28:28.7441296Z
JDStartCapture=2460409.311432
JDMidCapture=2460409.311438
JDEndCapture=2460409.311444
Duration=1.000s
FrameCount=1
ActualFrameRate=1.0000fps
TimeZone=-4.00
 
The image you posted is a greyscale bayer matrix image. If you run the Debayer process on it, you get:
1712744299512.png
 
You need to understand some basics here.
All the "colour" cameras (sometimes called One Shot Colour or OSC cameras) that you are likely to use for astrophotography do not actually produce colour images as their raw output. The camera is actually a monochrome sensor with an array of tiny filters in front of it, one for each pixel. Each pixel only has a single colour, determined by the filter in front of it. When you download a raw image from a camera, the image is actually a patchwork of monochrome pixels. For example, this is a close-up of the flare in your image:
1712753251199.png

If you colour each pixel with the colour of the filter in front of it, you get an image like this:
1712754121978.png

Note that each pixel is either red, green or blue - there are no colours in betwen. The array of RGB filters is called a Bayer matrix.
To produce a full colour picture, you have to guess the missing colours at each pixel; so at a red pixel, you have to guess the green and blue signal levels, and similarly for green and blue pixels. There are various different algorithms for guessing these values (based on the signal levels of nearby pixels of the appropriate colour). This process of guessing the values is called "debayering". In almost all astrophotography contexts with a standard OSC camera, the VNG algorithm ("Varying Number of Gradients" - don't worry why) is the best choice of algorithm.
When you run the VNG algorithm on your image you get a full RGB image:
1712754665297.png

You do this by selecting the Debayer process from the process menu and running it on the greyscale bayer matrix image.
When you capture sequences of deep sky images you will probably use the WBPP (Weighted Batch PreProcessing) script, which will usually be configured to perform debayering automatically at the appropriate point in the workflow.
 
Thanks very much. Another question. I have processed a lot of images in PI over the past year, and never before have I had to debayer any images. They just initially showed up as color, which was good. I haven't ever chosen to use the WBPP script. Any idea why I need to use the debayer process now (any idea what could have changed)? I'd like to set it to automatically debayer from now on.
 
jnatale said:
Thanks very much. Another question. I have processed a lot of images in PI over the past year, and never before have I had to debayer any images. They just initially showed up as color, which was good. I haven't ever chosen to use the WBPP script. Any idea why I need to use the debayer process now (any idea what could have changed)? I'd like to set it to automatically debayer from now on.
Click to expand...
Sounds like the same "bug" I have where RAW images that I open directly appear debayered. It's not supposed to work that way, it doesn't work that way for most people, and we've never identified a setting that would enable this.
 
cloudbait said:
Sounds like the same "bug" I have where RAW images that I open directly appear debayered. It's not supposed to work that way, it doesn't work that way for most people, and we've never identified a setting that would enable this.
Click to expand...

really? the RAW file handler has a bunch of checkboxes to control how RAW files are opened. if you go in there and click "Pure Raw" you should no longer have debayered files upon opening to the desktop. are you saying "pure raw" does not work for you?

jnatale said:
Thanks very much. Another question. I have processed a lot of images in PI over the past year, and never before have I had to debayer any images. They just initially showed up as color, which was good. I haven't ever chosen to use the WBPP script. Any idea why I need to use the debayer process now (any idea what could have changed)? I'd like to set it to automatically debayer from now on.
Click to expand...

left tabs -> format explorer -> double click "RAW". maybe post a screenshot of that control panel.

the short answer is that the RAW format explorer pane is a global setting for how DSLR images are opened. however, individual processes (like ImageCalibration) can override these settings with so-called "format hints". WBPP makes extensive use of these to make sure that no matter what the settings are in the RAW format explorer settings, the right thing happens (images must always be calibrated in bayered format and only debayered after calibration...)
 
pfile said:
really? the RAW file handler has a bunch of checkboxes to control how RAW files are opened. if you go in there and click "Pure Raw" you should no longer have debayered files upon opening to the desktop. are you saying "pure raw" does not work for you?



left tabs -> format explorer -> double click "RAW". maybe post a screenshot of that control panel.

the short answer is that the RAW format explorer pane is a global setting for how DSLR images are opened. however, individual processes (like ImageCalibration) can override these settings with so-called "format hints". WBPP makes extensive use of these to make sure that no matter what the settings are in the RAW format explorer settings, the right thing happens (images must always be calibrated in bayered format and only debayered after calibration...)
Click to expand...
I do recall that now. But it doesn't eliminate my "bug". All my raw files open already debayered (but not inside of processes) no matter what settings are there. There was a discussion about this not long ago here. Whatever is happening with my system is unresolved. But not a problem for me.
 
jnatale said:
They just initially showed up as color, which was good.
Click to expand...
Actually, if they show up as colour that is bad for astroprocessing, since for most astroimaging situations using a colour (OSC) camera, there are several pre-processing calibration steps that must be performed on raw (undebayered) images. You really need to adjust your raw settings to import raw format. My settings look like this:
1712761710799.png

You can get all the right settings in one click by selecting "Pure Raw".
It may seem odd that loading a colour image from a colour camera is wrong, but as you start processing sequences of deep space images you will soon understand why.
 
jnatale said:
I have processed a lot of images in PI over the past year, and never before have I had to debayer any images.
Click to expand...
You uploaded this as a fits file out of Sharpcap. How have you previously loaded files? Your Sharpcap parameters include "Colour Space=RAW16"; you may previously have selected an RGB option.
 
Thanks everyone. I figured out what happened (why this solar image showed up as black and white, as opposed to color). Previously, with other deep sky images, I had been stacking with DSS prior to processing in PI, and in DSS I had it set to debayer the files. But in this case (solar imaging) I was processing only one frame with no need to use DSS. So, since I didn't use DSS, it was black and white, since there was no debayering. But now I understand how to process an undebayered file in the future, if the need arises.
 
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