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Topics - M Covington

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For some time I've been using and refining my own version of the BatchPreprocessing script, with the following changes:
  - Has the ability to use bias frames as flat darks.  In DSLR photography, these are essentially the same and I use the same files for both.
  - Has the ability to apply a simple cosmetic correction without creating a process instance in advance.
  - Minor refinements to some error messages.

It is called BatchPreprocessingFD and is not quite in sync with the latest version of BatchPreprocessing, but I gladly offer it to the developers of PixInsight if they want to take features from it and add them to BatchPreprocessing. 

Available at:

Bug Reports / Two UI wishes
« on: 2018 July 29 10:37:27 »
These are wishes rather than bug reports.

(1) When a file is opened by right-clicking "Open With..." "PixInsight" (under Windows), PixInsight opens up with the process console on top of the picture.  Unless you think to minimize the process console, it is not obvious that the picture has been opened, since it's completely hidden.  I wonder if the process console should auto-minimize or the picture should open up in a different position on the screen.

(2) The defaults for saving as TIF are presently no compression, include alpha channel.  I have to change these every single time.  How about ZIP compression and no alpha channel if no alpha channel has been utilized?

Bug Reports / "Shared image reference" crashes
« on: 2018 July 29 10:35:02 »
I have been getting crashes with "Invalid shared image reference" or words to that effect, but so far, they have eluded my attempts to reproduce them.  They come after sessions in which I open a TIF file, work on it with at least 2 tools both using Real-Time Preview, save it under another name as TIF, and close it (getting the warning that although the image has not been modified since saving, there are unsaved process instances).  I understand that warning, click "yes," and then occasionally get the "shared image reference" crash.

If this is not a known problem I will be glad to investigate further.

Bug Reports / Typo in AutomaticBackgroundExtractor
« on: 2018 January 20 18:09:53 »
In the AutomaticBackgroundExtractor tool, "Minimum" is misspelled "Minimun".

I have taken the liberty of correcting this in a screen shot that will be an illustration for something I'm writing, in anticipation of your fixing it in PixInsight itself.

For those of us who regularly take flat darks rather than bias frames (the two are actually equivalent with many cameras), here is my humble attempt to improve the BatchPreprocessing script.  This version gives you a checkbox, "Bias frames are flat darks," which, when checked, causes the bias frames to be used not only as bias but also for dark subtraction of the flats.

This works whether or not you are optimizing darks.  When you are optimizing darks, it is not so necessary, because the regular darks are scaled to match the flats, but at least in theory (and I think in practice) this calibration is still a little better this way.

Presented to the PixInsight community with my compliments; feedback and improvements welcome!

This script is internally named "BatchPreprocessingFD" to avoid conflict with the original.  But I would like to suggest picking up this change into the distribution version, if the developers agree that it is useful.

UPDATE - Do not download this file - a corrected version was posted later.  Scroll down to that.

General / DSLRs, dark flats, and BatchPreprocessing
« on: 2018 January 01 18:22:36 »
I use DSLRs and take lights, darks, flats, and flat darks (not bias frames, although bias frames and dark flats are indistinguishable when the exposure time is something like 1/200 second, as mine are).

The BatchPreprocessing script seems to work fine when I put in the flat darks as bias frames.  I see from the log that the flats are calibrated with the regular darks (the darks that match my lights), which are scaled down by your noise analysis algorithm.

But I think I get even better results if I put some of my flat darks in as darks (and the rest as bias).  Because of the exposure time, they become a separate group of darks from the regular darks, and they are used to calibrate the flats.

BatchPreprocessing won't let me put the same files in more than one category.  However, I'm thinking of hacking it to add a checkbox, "Bias frames are flat darks," which would tell it to dark-subtract the flats using the master bias rather than the master dark.

A couple of questions about this...

(1) Am I on the right track here?  Should it work better that way?

(2) If I make the modified version of BatchPreprocessing, will I be free to distribute it?  Of course I can use anything for my own purposes, but I'm in the process of revising Digital SLR Astrophotography and want to give my readers a quick introduction to PixInsight, of which this might be part. 

If nothing else, I want to give good advice about how to use BatchPreprocessing in this situation.

Thanks in advance to those who are about to give helpful responses!

This is an icon problem different from what others have reported.

I have PixInsight pinned to the taskbar in Windows 10.  (Right-click on the tile in the Start Menu, choose More..., Pin to Taskbar.)

Since I upgraded to the latest version a couple of months ago, this icon became a white rectangle rather than the PixInsight diamond.

What I think is wrong is that one particular size of icon -- the one needed for display on the taskbar -- is missing or incorrect in PixInsight.exe.   [Probably not the case; see below.]

It may even have already been fixed -- I don't know.  It's something PixInsight updates would not be expected touch.  I'm going to re-download the whole installer and reinstall PixInsight.

Bug Reports / Bug fix, Batch Channel Extractor
« on: 2017 January 20 06:23:19 »
In a reply to my earlier posting ( I have included an improved version of the Batch Channel Extractor script.  Changes:

- Bug fix: Now able to write all output formats, not just .xisf
- Leaves console open while running so the user can see the progress messages
- Slightly smaller window for comfortable use on a 1024x768 laptop screen
- Version number incremented to 1.02.01

I hope the PixInsight team will consider distributing this in place of the currently distributed version.  This is my first attempt to contribute to PixInsight, and I hope I'm approaching it the right way.

It appears that Preprocessing->SplitCFA has a long-standing "bug" or undocumented limitation, which is that the image dimensions must be even numbers.  Also, no documentation of this particular menu item comes up.

Are there plans to remedy this?

Bug Reports / BatchChannelExtractor will only write .xisf files
« on: 2017 January 08 16:09:27 »
Bug in BatchChannelExtractor.js version 1.02.00

Symptom: Output is always a .xisf file regardless of the extension specified by the user.

Error message: Line 1091, trim is not defined

Looking back, I see that there was a brief conversation about this when BatchChannelExtractor was first contributed in 2010, but I'm not sure they got to the root of the problem.  Why would the "trim" function not be defined?  (I don't know JavaScript.)

Release Information / Why is latest download so much larger?
« on: 2015 November 27 13:58:03 »
I've successfully downloaded and installed today's upgrade to 1.8.4 for Windows.

Query: Why was the downloaded .exe file so much bigger this time?  140 MB versus 60 MB for 1.8.3 and a couple of earlier ones.

General / DSLR-friendly version of BatchPreprocessing script?
« on: 2015 November 21 10:06:57 »
I'm starting to use the BatchPreprocessing script for Canon DSLR work and wishing I had a slightly different version of the script with defaults more suited to the task.  Specifically:

"Add Bias" "Add Darks" "Add Flats" "Add Lights" should default to DSLR raw files only, not all file types, and should accept files even though there is nothing in them marking which kind of image they are.  (Right now I have to add all four kinds with "Add Custom.")

"CFA image" should be checked, or even presumed (doesn't need a checkbox).

Maybe a few other little things.

It would not be hard to make a modified edition of the BatchPreprocessing script, or maybe add a checkbox that would flip all of the defaults to be more DSLR-friendly.  Is anyone working on this?

Going further, I would wish for a calibration algorithm that uses lights, darks, flats, and flat darks, but not bias frames, since that is the way I'm doing it with DeepSkyStacker.

If I only had time!   :)

General / Simplest way to boost saturation
« on: 2015 January 19 08:05:52 »
What is the simplest way to boost color saturation all over a picture, for all hues?  I'm looking for something analogous to +20 saturation in Photoshop or +20% saturation in DeepSkyStacker.  The specific need is DeepSkyStacker autosave.tif files, which have unusually low color saturation and always require boosting.  Thanks!

General / Taking DSS Autosave.tif into PixInsight
« on: 2015 January 10 11:48:57 »
Esteemed colleagues,

I am using PixInsight to postprocess the output of DeepSkyStacker (originally coming from a Canon 60Da).  It works well, but the DeepSkyStacker Autosave.tif file is very dark when opened with PixInsight, as if it weren't using the whole bit depth of its file format.  I can manually adjust it with Intensity Transformations -> Histogram Transformation but was wondering if there was a shortcut.

Also, I am under the impression that if I adjust brightness, saturation, etc., in DeepSkyStacker and save the file, it doesn't have as much bit depth as it claims to.  I see banding in shaded areas, for instance.  This was described as a problem with earlier versions of DeepSkyStacker some time back; does anyone know if it's still present?

I am using the latest DeepSkyStacker, version 3.3.4.


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