Help with Canon T3i RAW Settings

[ZephanRC]

I am new to using PixInsight and have been going through the DSLR_RAW work flow (http://pixinsight.com/forum/index.php?topic=2570.0).
It seems there is some question as to which RAW format preferences to set.  Either "Create RAW Bayer" or "Create Raw Bayer CFA".  I tried both with a "normal/non-astro photo" and in either case when I debayer the imported CR2 file the result has a green hue to it.

What am I doing wrong and which RAW format preference should I use for my Canon CR2 files?

See attached.

[ZephanRC]

Just to add to this....  If I change the RAW format settings for VNG Interpolation (below), then the CR2 file seems to import with a proper color balance (below).  Why whould the importing with no debayering (either RGB or CFA) and then debayer the imported image produce the same thing?

[georg.viehoever]

- As far as I know, the debayer processes/scripts expect a monochrome input, so use "Create RAW Bayer CFA" in this case.
- Dont worry about the color tint. You usually fix those using the BackgroundNeutralization/ColorCalibration processes for Astrophotos. For daylight images, you could use HistogramTransform.
- I dont know why VNG produces a nice color balance. Did you play with "Auto White Balance" in the RAW format dialog?
- If you goal is calibration of images, use the BatchPreProcessing script (in the scripts menu) instead iof the manual DSLR_RAW flow. If you are a beginner, I would recommend to use DeepSkyStacker to do you stacking.

Georg

[ZephanRC]

- As far as I know, the debayer processes/scripts expect a monochrome input, so use "Create RAW Bayer CFA" in this case.

I can't seem to find the message, but I believe Juan stated that the latest debayer processes (and batch debayer script) now handles either RGB or CFA bayer images and that the RGB bayer images are better for calibration.  True?

- Dont worry about the color tint. You usually fix those using the BackgroundNeutralization/ColorCalibration processes for Astrophotos. For daylight images, you could use HistogramTransform.

Ok....  I can live with that.

- I dont know why VNG produces a nice color balance. Did you play with "Auto White Balance" in the RAW format dialog?

My problem/question here is why would importing the CR2 with the VNG interpolation preference does not produce the same thing as importing with no interpolation and then debayer with VNG interpolation?  Shouldn't it be the same thing?

My understanding is that you don't want to use any White Balance adjustments to your RAW image imports/conversions to avoid any potential lose of original data.

- If you goal is calibration of images, use the BatchPreProcessing script (in the scripts menu) instead iof the manual DSLR_RAW flow. If you are a beginner, I would recommend to use DeepSkyStacker to do you stacking.

My understanding is that the BatchPreProcessing uses CFA bayer images and, as I stated above, I thought that the RGB bayer images were better for calibration (wish I could find where I thought Juan mentioned this).  By the way, I am also unclear how using the "raw" input hint in either the ImageCalibration or ImageIntegration tools affects what is set in the RAW format preferences or not.

One of the major reasons for wanting to use PixInsight versus DSS was to have more control over the calibration and stacking of my RAW images (dark auto scaling in particular).  PixInsight has some awesome post processing capabilities and I'd like to use one tool for everything.

[pfile]

white balance adjustments are just multiplicative factors, and they are in the EXIF data only. they do not affect the recording of the raw image.

don't forget that there are two green pixels in the bayer matrix, for psychovisual reasons. the SNR of the green channel is going to be the highest in any image taken with an OSC. this probably is responsible for the green cast.

lots of stuff goes on behind the scenes in a terrestrial photography program that PI is not doing. i wouldn't worry too much about the color balance.

[ZephanRC]

I know that this must be my noob level of experience with PI (by the way I am finding this program awesome!), but I'm still not quite sure how Canon CR2 RAW files are handled.

Im ok with the whole color balance thing when displaying the imported RAW files (either as RGB or CFA grayscale), but I still have question as to which RAW format preference I should use during calibration and integration of my files (B,D,F & L)?

Reading this topic/message (http://pixinsight.com/forum/index.php?topic=2268.msg14959#msg14959), I get the impression that using the "Create RAW Bayer image (RGB)" is my "best" choice while calibrating/integrating all of my files.  But if I do use RGB Bayer images, do they have to be "manually" converted to CFA grascale first before DeBayering?  At the end of this message it states:

"So the solution is a script. I have modified Ken Pendlebury's BatchDebayer script to implement this conversion. The whole task is carried out automatically; the script detects a RGB Bayer image and performs the required steps in a completely transparent way, so you only have to select your calibrated images, select an output directory, and click OK. I'm going to post the modified script on the New Scripts and Modules board in a few minutes."

What I am still wondering about is:

Does the BatchDebayer script in the latest version of PI include the mod to handle RGB Bayer images?

Does the DeBayer process (versus the batch script) also handle either RGB or CFA Bayer images?

Does the BatchPreProcessing script convert DSLR RAWS to RGB or CFA during processing?

Is it still best to use RGB bayer images versus CFA monochrome for calibration/integration?

How does all of this relate to using the "raw" format hint in the process dialogs?

[pfile]

short answers, yes, yes, yes and i don't think it matters.

at some point Debayer and BatchDebayer only handled monochrome images but at some point in the past it was upgraded to handle 3-plane RGB raw (bayered) data. so PI should be able to handle either raw format no problem now.

generally speaking, calibration of CCD images must be done on raw data. for a OSC camera this means that the calibration must occur on bayer images, either CFA or RGB. immediately after calibration, you then debayer the subs, register them and finally integrate them.

IIRC the format hint "raw" is the same as configuring the CR2 reader to produce bayered RGB data with no black point compensation.

i don't think it matters whether you use RGB raw or CFA raw. i always used to use RGB when manually doing stuff but it seems that the BatchPreprocessing script wants to use CFA for OSC data.

[ZephanRC]

Thanks pfile!

I'm a bit slow at this stuff, but I think I follow.  Just to make sure I get it:

I can use the BatchPreprocessing script and load all of my images (Bias, Darks, Flats and Lights) as CR2 raw files just as them come from my camera?  I will end up with Master Bias, Dark and Flat files that I can use for later batch processing as well as a debayered/registered/integrated image for further post processing?

[pfile]

yep, that is correct.

the only caveat being that the integrated result out of BatchPreProcessing should just be considered a preview. if you are using a stacking method which uses an outlier pixel rejection scheme, you always need to experiment with the rejection controls to make sure you're really rejecting only true outliers.