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Messages - GaryP

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General / Re: Which version to download for an antique system?
« on: 2019 November 28 14:31:55 »
Hi Gary,

No current version of PixInsight can run on Mac OSX 10.9. The minimum supported version is macOS 10.12. The latest version 1.8.7 requires a processor with SSE4.2 instruction support, so your Core 2 Duo CPU cannot run it. Time to get a new machine!


I thought a bit about the installation of the new version of PixInsight and realized I might be able to reinstall my old version by recovering it from a backup drive and dropping it into Applications (after removing the inappropriate new version). This seems to work so I will limp along with my antique system for a bit longer.

General / Re: Which version to download for an antique system?
« on: 2019 October 02 12:10:38 »
Hi Juan,
I fear my question may have been misunderstood. I was not asking for a current version. I downloaded a new version and followed the install instructions to jettison the Pixinsight folder from Applications. After installing I got the bad news that the new version would not work on my Mac. The original version is gone from the Trash bin. So now I am without PI. I simply wanted to reinstall an old version that will work. Since the vintage software seems to be unavailable, it looks like I will be deprived of PI until such time in the future as I can justify the expense and fuss of a new computer.

General / Which version to download for an antique system?
« on: 2019 October 01 16:50:31 »
I'm still clinging to my late 2009 iMac until it dies and running OS X 10.9.5. What is the latest version of Pixinsight that will run on it?

General / Re: Frustrated by active dynamic interface
« on: 2018 October 28 08:17:13 »

Did you every figure out how to fix the dynamic interface issue?


It's been quite a while since I used it. I don't think I did get it adequately sorted out, but I did a lot of work with the program and I plan some more, so I will probably encounter the issue again.

@Rob/pfile, no dispute, but some puzzlement as to why I might have installed it, since the Apple unzip works so well.


I guess we persist in using Zipeg because we weren't aware of another way. I was still not aware of it until your most recent reply. Zipeg comes with the OS, so double clicking on the zip file brings up Zipeg. Those of us who don't spend much time researching how our OS works have been conditioned to believe that is the natural order of things, but apparently it is just a form of product placement. Thanks for the information. I will dump the Zipeg.

Perhaps this will save someone else a couple of hours. Some users of PixInsight may have a minimal understanding of command lines and a few may have none. Mine is pretty minimal and very rusty.

I tried several times to install on OS X 10.9.3 Mavericks, sometimes by extracting it in Zipeg and saving the extraction files into /Applications, other times by saving the zip file first to the Downloads folder and then extracting, or by saving to /Applications and then extracting. I tried rebooting after extracting and waiting overnight to ensure that the download completes. The result was always the same, a small window with the message:

“The Pixinsight Core application has been launched from a directory that does not meet the requirements of a valid PixInsight distribution.”

I noticed that Gerry Doyle in Reply #18 on this thread said: “I'd used a 'Zipeg' app to unzip the download - this time round I used the embedded OS X utility and it unzipped properly.” I noticed that J.C. supported this method. I didn’t know what utility Gerry was referring to. The only relevant one that appears in my utilities folder is Zipeg. So I guessed he must have referred to the unix utility unzip or maybe zcat. Following an OS X manual, I opened the terminal program and tried zcat and failed to get results. I browsed online and found a recommendation to type “unzip” into the terminal and then drag the .zip file to the terminal window, drop it on the line, and hit return. This produced the desired results. I located the new PixInsight folder, dragged it to Applications, dropped it in, and as I type this, fifteen upgrades are downloading from within PixInsight.

General / Re: SNR
« on: 2014 August 07 10:23:49 »
Mike, you needn't worry about oversimplification in my case. It's nice to be guided around among the pixels at level 1. It will certainly do until my copy of Berry and Burnell arrives.

General / Re: SNR
« on: 2014 August 06 14:41:30 »
Good to know. Used copies are available at about $80.

General / Re: SNR
« on: 2014 August 06 08:17:49 »
That helps. No further questions. It would be nice if someone would use a forum thread to provide an online primer on wavelets, which are used in several important scripts and functions. That might help many users to make more intelligent use of PixInsight. "Wavelets for Image Processing".

General / Re: SNR
« on: 2014 August 05 23:29:57 »
Mike, Thanks, It's good to know that the procedures made some sense, but please bear in mind that you are dealing with someone who knows next to nothing about the theory of image processing.

>The N number in the script output is the number of pixels in the image used to measure noise.

Why does this number vary? Or if it is the same as the number of pixels containing noise, how are those pixels identified?

>J is the number of multiscale levels used to distinguish these pixels.

I don't understand what this means, but it appears to have some bearing on my previous questions. What is a "multiscale level"?

>IMO, AvgDev / MRSNoise, as you are calculating, is usually a good measure of image quality, a good way to characterize SNR, but it is not the SNR of anything in the image of course. It is a "scale" to noise ratio, where scale is image dispersion, a measure of the typical distance between any pair of pixels in the image. AvgDev is one of several ways to measure scale, others are preferred sometimes for more robustness (see the list in ImageIntegration).

Does this mean there is no good way to measure "signal"? Or is this really a better way of characterizing image quality than a more direct SNR measure?


General / SNR
« on: 2014 August 05 21:55:56 »
I made three different stacks of IC1396 with a DSLR camera, and I want to make sure I'm working on the best stack. One of the stacks is a reregistered integration of the other two. I've been trying to figure out how to use PixInsight to determine SNR. One message from an apparent expert on the PI forum says use AvgDev for the signal and MRSNoise for the noise and then do the division.

I found AveDev in the Statistics readout. Notice there is not a whole lot of difference in the stacks. July 25 has the edge.

Table 1: AveDev from Statistics, 3 Stacks
   R   G   B
Jul 25:   1.21e-03   8.79e-04   6.86e-04
Jul 27:   1.13e-03   8.05e-04   6.37e-04
combi:   1.20e-03   8.65e-04   6.61e-04

MRSNoise is supposed to be in NoiseEvaluation, a script that just runs immediately on an open image and displays its results on the console, but I don't find anything called MRSNoise in it. Here is a readout from the console for the combined stack.


Calculating noise standard deviation...

* Channel #0
?R = 9.237e-05, N = 186299 (1.23%), J = 4

* Channel #1
?G = 7.597e-05, N = 397750 (2.62%), J = 4

* Channel #2
?B = 8.241e-05, N = 884136 (5.83%), J = 4

So maybe MRSNoise refers to the sigma values above (?sigma = mean root square). What, exactly, does N refer to? Table 2 gives the sigma values.

Table 2. Sigma values from NoiseEvaluation, three stacks

   R   G   B
Jul 25:   1.305e-04   1.079e-04   1.115e-04
Jul 27:   1.385e-04   1.137e-04   1.180e-04
combi:   9.237e-05   7.597e-05   8.241e-05

Notice the smaller noise values for the combination stack. Now we can do the arithmetic for SNR:

Table 3. Signal to noise ratios (AveDev/Sigma), three stacks

   R   G      B
Jul 25:   9.27203, 8.14643, 6.15247
Jul 27:   8.15884, 7.08004, 5.39831
combi:   12.9912, 11.3861, 8.02087

In my very limited experience, those look like plausible SNR values. We see that Jul 25 beats Jul 27 in every channel in spite of better seeing on the 27th, but the combined stack of 69 subs beats them both by a substantial amount. This is due mainly to dividing similar signal values by lower noise values in the combined stack. It may be the case that some difference in calibration parameter settings had something to due with getting those noise values down, but my records are not good enough to say.

I know little about any of this. I would like to know if what I have presented makes any sense.

Announcements / Re: PixInsight Benchmark
« on: 2014 May 19 10:21:51 »
I can't answer any of your questions, but it makes interesting reading and provides a description of what performance can be obtained with 16 GB with or without a RAM disk and varying sizes of batches. It is useful in anticipating how long a process might take.

Announcements / Re: PixInsight Benchmark
« on: 2014 May 18 17:27:46 »
You are right of course. In my case the second SSD would be SATA III like the first. While drive speed is important to overall swap speed I think the point here is that a ram disk will be MUCH faster than even the fastest drive.

The question is the trade off of that ram not being available for other uses and the limited size of the ram disk relative to physical swap drives.

That helps to put things in perspective. Thanks.

Announcements / Re: PixInsight Benchmark
« on: 2014 May 18 15:06:30 »
Would that second SSD be internal or external, and if external, USB II or III, Firewire, or Thunderbolt? Not that I could answer your question in any case, but it must make a large difference.

I will have to do some "real world" testing of my own to see how far my little 4gb ram disk goes. It's still not clear to me what the better investment would be. Add 16GB as a ram disk ($140) or a second SSD ($90).


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