OSC and not debayering

Yes, I think you can do so using the "no interpolation" option in tab 0, for the used demosaic algorithm.

 When I click the "no interpolation" about 50% of my lights fail star analysis. Running a normal calibrate and register no lights fail analysis.

@tsprecher It seems that this currently isn't possible. The interpolation drop down in the normalization tab doesn't allow for not debayering the frames. I'll pass this on to Mabula and will ask if that can be added.

FYI - The purpose of this exercise was to provide calibrated, registered non debayered frames from a OSC to a  program that will plot a light curve of exoplanets.

Thanks for the response.

Hi Thomas @tsprecher,

That is simply not possible in APP at the moment.

The reason being is that the frames require debayering to not have bayer holes in the star intensity profiles so APP can accurately find the star centroids to have precise star alignment in registration. Without debayering this simply is not possible, without debayering you miss essential precision on the star profiles. The precision drops from about 0,1 to 0,5 pixel precision. Without debayering, you indeed will see that APP can't register them because of the bayer holes in the star intensity profiles.

Furthermore, the frames are registered, meaning the frames have been rotated, translated, scaled, corrected for optical distortion (so warped) etc... so the data is being resampled/interpolated to account for subpixel changes in all of these registration parameters combined.

A solution would be that APP would then allow you to save registered frames where only the bayer pixels are then filtered with a resampling/interpolation filter like Lanczos. But.... since the registration parameters will rotate, translate, scale, warp the resulting pixels, you can never again debayer that reliably. I would not know how... You could only do a naive and thus worse nearest neighbour on the pixels that were still zero. Realise that the registered bayer pixels because of the otate, translate, scale, warp will no longer have a nice Bayer pattern.. so no normal debayer algorithm can fix that.

Can I ask why you want that data not to be debayered? Is the convolution effect of debayering your concern?

Mabula

@mabula-admin

I am using two programs, AstroimageJ and HOPS. Both are designed to take images from a mono ccd camera and plot the small flux changes of a star recorded from an exoplanet transit. They only take darks, flats and bias for calibration. I want to use my ASI533MC OSC and darks, flats and darkflats for calibration and present mono images (could be 100 to 200 images) to these programs. So my thought process was to use APP to calibrate and register the images and bypass that part of the process in those programs. Maybe my thinking is off on how to do this as I am not an expert.

Thomas

@tsprecher If those two software packages really only can process mono data then there is a possibility to prepare the images with APP. In tab 0 you can choose the "no interpolation" algorithm, which will force APP to treat all data as mono data. You can then process up to tab 5 Normalization and save the normalized images, which will be mono.

Note, however, that an OSC camera has a different response than a mono camera, since the pixels are grouped together in Bayer matrices. This mean, as you probably know, that one pixel is sensitive to red, two to green and one to blue. This means that using "no interpolation" will generate mono images but not with the same response as a true mono camera. For instance, red or blue stars may look brighter in the OSC mono images than in true mono images, depending on the filter used in the mono camera.

@tsprecher Out of curiosity, do you have a URL for HOPS? I have been searching online and cannot seem to find it.

@wvreeven 

Link to HOPS

https://www.exoworldsspies.com/en/software/

Note: I have used my raw images and calibration frames with both programs and obtained results. I just want to see if calibrating and registering them differently will provide better results, as sometimes some of the raw images are rejected. Also, APP wipes out a lot of the fits header info which is needed.

Thomas

Posted by: @tsprecher

Link to HOPS

https://www.exoworldsspies.com/en/software/

Thanks. I found that site but wasn't sure if it was the same software as you meant.

@wvreeven 

I tried running APP again using the "NO Interpolation" and was successful in obtaining gray 16 bit mono calibrated/registered images with a different data set. (I tried this initially as Vincent suggested-somehow I screwed up!)  Now I need to start from scratch with a data set that has more exposure and see if these other programs will except the data. Thanks for all the help!