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Messages - wvanreeven

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Gallery / Re: coma cluster - C14 Hyperstar EOS 60Da
« on: Today at 04:48 »
Very nice and deep image! One issue with the images is not related to the processing: the stars are not round apart from in the lower right corner indicating a slight miscollimation or tilt of the sensor. Otherwise very nice for such few, short exposures!


General / Re: best time to debayer?
« on: 2019 July 11 04:45:55 »
I was assuming one does the preprocessing with darks and flats and bias, as usual with the bayered subs and  debayer them at some special point in the process maybe when preprocessing is done. Now I don't know. The answers here have confused me, I am kinda a newbie at this. I never even realized that darks etc are also bayered. I have to read these replies some more and hope for more enlightenment. A step-by-step maybe  ;D

James, sorry for the confusion. Any image taken with a color sensor will have the Bayer pattern encoded so that includes darks, bias and even day-time images. DSLR cameras normally debayer the day-time images for you so that's why nobody notices that the RAW files actually are composed of Red, Green and Blue pixels.

CMOS astronomical cameras do not have the functionality of auto-debayering and that's why this needs to be done at some point in the image processing chain. As a matter of fact, when using a DSLR the RAW images should be processed. And in both cases is recommended to do this as late as possible in the processing chain because debayering involves assigning a colour to each pixel based on the surrounding pixel values for the different colours Red, Green and Blue and that value depends on the debayering algorithm used though the differences are small.

So, please have a look at the workflow that I outlined in my first replay and take Bernd's remarks of his first reply into account and you should be fine.


Gallery / Re: 2019 Solar eclipse from Punta Colorada, Chile
« on: 2019 July 11 02:11:07 »
you got a very nice result there, especially for the moon's surface.


You may want to try the Larson-Sekanina filter to try to bring a bit more of the details in the corona.

Thanks for the suggestion of the Larson-Sekanina filter! I applied it quickly to my images and indeed much more details become visible in the corona. However, the Moon gets very much distorted so I will need to fix that afterwards. In any case I'll need to investigate the options of the filter in order to get the best results.


General / Re: best time to debayer?
« on: 2019 July 11 01:41:18 »
On top of Rob's excellent explanation, some cameras suffer from amp glow and this doesn't seem to be linear as well. Properly taken darks can eliminate this but this again requires different darks for different exposure times. Again, DSLR cameras don't suffer from this but I wanted to add this comment in case owners of other cameras read this thread.


General / Re: best time to debayer?
« on: 2019 July 10 11:09:21 »
This problem occurs with DSLR cameras and astro cameras with CMOS sensors (my experience with Canon EOS 600D, ASI294MC Pro and ASI 071MC Pro). The approach not to pre-calibrate the darks (or the MasterDark) should work independently from the used sensor. Maybe that cameras with a CCD sensor do not suffer from this issue.


Perhaps indeed that CCD cameras don’t suffer from this but I have only imaged with Canon cameras and never had the issue. Or perhaps I did and I never realised it! Anyway, thanks once more for the reminder. I’ll review my processing workflow.


General / Re: best time to debayer?
« on: 2019 July 10 10:39:16 »
Yes I have seen that topic but frankly I never had any problems calibrating darks with the master bias. Anyway, thanks for the reminder!

General / Re: best time to debayer?
« on: 2019 July 10 09:06:58 »
Bias, dark amd flat frames should never be debayered. Simply integrate the bias frames to a master bias, calibrate the darks with the master bias, integrate them to a master dark, calibrate the flats with the master bias and dark and integrate them to a master flat.

Then calibrate the lights with the three masters, perform cosmic correction, debayer, star align and integrate. Between star alignment you may opt for local normalization. After integration you may opt for drizzle integration and in order to do that you need to have Generate Drizzle Data enabled in both Star Alignment and Image Integration.

HTH, Wouter

Gallery / Re: 2019 Solar eclipse from Punta Colorada, Chile
« on: 2019 July 10 08:02:37 »
Great workflow Carlos and I am afraid it is way out of my league. In the end I managed to create decent HDR images using Photomatix Pro. The images have been posted on my Facebook page ;-)

Gallery / Re: 2019 Solar eclipse from Punta Colorada, Chile
« on: 2019 July 09 22:04:24 »
Very nice! Would you mind sharing some of the secrets of creating the HDR composition with us? Was that all done in PI? If yes, how did you align the subs? Many thanks in advance since I am struggling to combine my own bracketed pics.


General / Re: making color images from CR2 files
« on: 2019 June 24 23:54:19 »
I think in the preferred workflow ImageRegistration should (also) be ImageIntegration. Furthermore StarAlignment should be done before ImageIntegration. In other words:

or (preferred):
- Debayer (= conversion to RGB image),
- StarAlignment (option 'Generate drizzle data' enabled),
- ImageIntegration (option 'Generate drizzle data' enabled),
- Drizzle Integration (option 'CFA Drizzle' enabled).


General / Re: Blue/white artifacting stars
« on: 2019 June 14 07:03:16 »
Ah wait I hadn't seen that you were using small band filters. Then please ignore what I wrote about imperfect optics because that only comes in play with broad band imaging.

General / Re: Blue/white artifacting stars
« on: 2019 June 14 06:42:44 »
Did you refocus when switching to the blue filter? I suppose you did.

It may be a blue halo caused by imperfect optics. I had the same problem with my WilliamOptics ZS71 ED.

General / Re: Why does STF do this?
« on: 2019 June 04 23:49:11 »
You could either save the resulting image after each applied process/script (this is what I do but it generates a LOT of images which consume a LOT of disk space) and then load the image of which you'd like to apply the STF of (first apply STF on the image that you loaded and then apply the SAME STF on your latest image) OR press ctrl-z several times until you're back to the step where you got a good STF and then press ctrl-y again to apply the processes/scripts again (not sure if this always works since I don't know if all processes/scripts allow for this).

HTH, Wouter

Wish List / Automatically create output folders
« on: 2019 May 16 00:30:47 »

Processes like ImageCalibration, CosmicCorrection and StarAlignment allow for outputting the processed files in a selected directory. Currently these output directories need to exist in order for the process to work correctly. However, when processing images taken with multiple filters (L, R, G, B and Ha in my case) it would be very handy if the process could create the directories if they don't exist. I always keep the files for the individual filters in separate directories in order not to mix up the files and mistakenly add e.g. green filter lights to the ImageIntegration run for the blue filter. Prior to invoking the process (either by clicking the circle button or pressing F6) one could then clear the list of target frames, add new ones, manually change the output directory and hit F6.

This of course now can be achieved by actually creating the directories beforehand but this is cumbersome and error prone. Thanks very much in advance for considering this.

Clear skies, Wouter

Wish List / Make select all work on macOS
« on: 2019 May 16 00:08:03 »

In any process or script that requires multiple input files, the CMD-A and CTRL-A key combinations do not work on macOS when trying to select all files in a directory. Instead I have to select the first file, scroll down to the last file and click on the last file while holding the shift key.

Would it be possible please to make either CMD-A or CTRL-A (or both?) work on macOS? Many thanks in advance for considering this.

Clear skies, Wouter

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