Pixinsight Debayering Question

[Stonius]

Hi,

I'm a complete noob at this. I've been following a tutorial on PixInsight, and I can't figure out how to output to colour files. Once I use the format explorer and tell it to look at my canon's CR2 files as Pure Raw, everything in the interface is in Black and White. Do I still need to explicitly debayer? I don't know. The tutorial seems pretty light on that section assuming I'd already have done it if need be. Every tutorial I can find on it lists about 5 other tutorials first, essentially 'learn the entire rest of the program for this little bit to make sense'.

The Data is about 740 lights taken from an unmodded Canon 5D Mk11. No tracking. 4 Sec Exposures with a sigma Art 50mm f1.4. I did 20 each darks, flats, and bias.

This is the tutorial I've been following. http://www.lightvortexastronomy.com/tutorial-pre-processing-calibrating-and-stacking-images-in-pixinsight.html
which uses this basic workflow;
Stacking many bias frames to produce a master bias.
Stacking many dark frames to produce a master dark.
Stacking many flat frames to produce a master flat.
Calibrating the master flat with the master bias and master dark.
Calibrating light frames with the masters, removing hot and cold pixels, registering and stacking the resulting calibrated light frames.
Applying a resampling algorithm such as Drizzle to improve the end result.

I haven't explicitly debayered anything because I'm not sure if I have to having set up the Format Explorer, but also becaus eI'm not sure what the Bayer format of the Canon 5D Mkii is.

Thanks for any help.

Markus

[sil]

from the tutorial you are following : "PixInsight reads DSLR RAW colour images as Debayered images, meaning it is artificially altering them to display them in colour within PixInsight. "


"Please note that now opening DSLR RAW colour images in PixInsight will display them in monochrome, such as is the RAW image data. Once the images are calibrated, we will be converting them to colour images by Debayering them so do not worry about this."


Sounds like you haven't followed the entire tutorial yet and/or havent understood.the tutorial talks about things you need to do or not do depending if your images are rgb or mono meaning they were captured with a colour or monochrome camera rather than how they look at that point in the tutorial.. or are expecting spectacular results already in intermediate steps. A good workflow only comes together visually near the end. the LVA tutorials are very good and robust and do require some skill and knowledge up front as they point out.

[RobF]

Hi Markus,

Yes, you'll need to do a batch debayer as the very first step, before anything else. You could check your matrix choice using the script at:

Script/Batch Processing/Batch DeBayer

Once you're getting proper RGB files, the best option to probably just use the Batch PreProcessing script - which will debay, calibrate, stack etc for you - then you can concentrate on processing your stacked master image.
(note: the real gurus play with the final stacking settings to optimize signal to noise, but the defaults usually work well, especially while you're learning)

[Stonius]

Hmm. Okay, I thought the Format Explorer/DSLR_RAW/Edit Preferences/Pure Raw/Create raw Bayer CFA/RGB image would take care of that internally, but maybe not. So the debayering creates separate RGB files on the disk. I assume I'd then run the tutorial 3 times on each colour then integrate the three colour masters at the end?

Markus

[Stonius]

So does this mean I need go back and debayer my darks, flats and bias frames too?

[Camelopardalis]

No - you should calibrate before debayering. Only debayer prior to registration.

[Stonius]

Thing is, it says to enable the CFA option in the ImageCallibration process, but that option doesn't exist in my version (01.08.04.1195)

"If your light frames are colour images from a one shot colour CCD camera or DSLR camera, enable the CFA images (Colour Filter Array) setting here. These images will be Debayered later in the pre-processing workflow. "

Not sure what to do when the tutorial doesn't reflect the interface...

Markus

[Camelopardalis]

It's the Cosmetic Correction module that has a CFA option (see the pictures in the article :P ) not the Image Calibration module.

[Stonius]

Dunk, thanks. I'm back on track now. Sometimes it takes another pair of eyes to point out the bleedingly obvious!

Markus

[Camelopardalis]

Yeah wood and trees and all that :thumbsup:

[RobF]

Apologies for the assumption Batch PreProcess debayers first. Dunk is correct to say needs to be just before registration.

More info here, if of interest:
https://pixinsight.com/forum/index.php?topic=3797.0

[rcheshire]

The steps in simple terms are;

1. Pure RAW - a monochrome (RGB channels intact) image with the color filter array intact
2. Calibration - single channel - less memory
3. DeBayer - interpolate the RGB pixel values to create a color image
4. Register
5. Integrate

A monochrome image does not necessarily imply no color information, but I guess that is understood.

Calibration prior to calibration is possible but not a good idea. Debayering without median reduction introduces color artefacts, while three channels consumes lots of memory.

Furthermore, when using the traditional PI image reduction method (dark scaling) keep in mind it may produce poor results with some DSLR RAW data sets. A different approach is necessary. Proper acquisition is the key.