CALIBRATION - BASIC QUESTIONS (CFA / RGB)

[dpaul]

I've started a new topic to help with some fundamental questions -

I'm currently using a One-shot-color camera (CMOS) and it seems at the moment I can't save data as true RAW (setting DSLR Format Explore as 'pure RAW makes no difference) - whatever is saved comes out as RGB.

So here are some basic questions if the experts can help me:

1/. I believe calibration of light frames with bias, flats and darks is bets done in pre-debayered state (CFA-color filter array), but must it be? Can a result although maybe not ideal be still achieved with RBG files for everything?

2/. Is there a way to convert RGB data to FCA (in PixelMath or Debayer Process?) so essential the reverse what is normally needed?

I only recently started calibrating the light frames. I started last week and and captured Master Bias and Master Darks. The Bias actaully seems to make a big different on the final result so even as an RGB master bias, it seems to be reducing the final noise result. The Darks I'm having more problem where the calibration process says the darks are incompatible with light frames. I reposted the Master Dark which shows a sudden drop off to the left.

Thanks in advance for the help

David

[bulrichl]

Hi David,

for an OSC camera the manufacturer of the camera typically includes a software for the acquisition of images. This software has to be set-up for the saving of monochrome CFA images, usually as FITS files. Have a look at the manual of the camera. In case of doubt ask the manufacturer of the camera or the distributor where you purchased your camera.

The set-up of RAW_DSLR in PixInsight's Format Explorer as 'True raw' will not help here. This is only for DSLRs which are using a proprietary format for the raw files (e. g. NEF for Nikon cameras or CR2 for Canon cameras).

The processing of astro images should always start with the "raw" images. As I already outlined in your other thread "Deconvolution & Bias Frames", the de-bayering has to be done just before registering of the calibrated light frames and not until the calibration process is completed. To process already de-bayered images in the calibration is not a good alternative and should definitely be avoided.

Bernd

[dpaul]

Thanks Bernd

That's the answer I expected.

Regards

David