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Messages - vicent_peris

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... making progress ...

One more question: is it possible to capture the process output?

Yes. Type "help log" in the Process Console. You can execute the log command in the SCP file to control the output of the ImageIntegration process. Once you exit PixInsight, you can then analyze externally the log file.

Hi Mark,

If you want to populate a group of machines with PixInsight instances running specific processes, I think the best way is to write bash scripts that send the commands to each machine. This would be a good approach IMO:

First, we write a small JavaScript script to be run in each PixInsight instance. This script is simply an execution of an ImageIntegration instance with a set of known parameters:

Code: [Select]
var P = new ImageIntegration;
P.images = [ // enabled, path, drizzlePath
   [true, "/home/vicent/Image01.xisf", ""],
   [true, "/home/vicent/Image02.xisf", ""],
   [true, "/home/vicent/Image03.xisf", ""],
   [true, "/home/vicent/Image04.xisf", ""],
   [true, "/home/vicent/Image05.xisf", ""],
   [true, "/home/vicent/Image06.xisf", ""],
   [true, "/home/vicent/Image07.xisf", ""],
   [true, "/home/vicent/Image08.xisf", ""],
   [true, "/home/vicent/Image09.xisf", ""],
   [true, "/home/vicent/Image10.xisf", ""],
   [true, "/home/vicent/Image11.xisf", ""],
   [true, "/home/vicent/Image12.xisf", ""]
P.inputHints = "";
P.combination = ImageIntegration.prototype.Average;
P.weightMode = ImageIntegration.prototype.NoiseEvaluation;
P.weightKeyword = "";
P.weightScale = ImageIntegration.prototype.WeightScale_IKSS;
P.ignoreNoiseKeywords = false;
P.normalization = ImageIntegration.prototype.AdditiveWithScaling;
P.rejection = ImageIntegration.prototype.WinsorizedSigmaClip;
P.rejectionNormalization = ImageIntegration.prototype.Scale;
P.minMaxLow = 1;
P.minMaxHigh = 1;
P.pcClipLow = 0.200;
P.pcClipHigh = 0.100;
P.sigmaLow = 4.000;
P.sigmaHigh = 3.000;
P.linearFitLow = 5.000;
P.linearFitHigh = 2.500;
P.ccdGain = 1.00;
P.ccdReadNoise = 10.00;
P.ccdScaleNoise = 0.00;
P.clipLow = true;
P.clipHigh = true;
P.rangeClipLow = true;
P.rangeLow = 0.000000;
P.rangeClipHigh = false;
P.rangeHigh = 0.980000;
P.mapRangeRejection = true;
P.reportRangeRejection = false;
P.largeScaleClipLow = false;
P.largeScaleClipLowProtectedLayers = 2;
P.largeScaleClipLowGrowth = 2;
P.largeScaleClipHigh = false;
P.largeScaleClipHighProtectedLayers = 2;
P.largeScaleClipHighGrowth = 2;
P.generate64BitResult = false;
P.generateRejectionMaps = true;
P.generateIntegratedImage = true;
P.generateDrizzleData = false;
P.closePreviousImages = false;
P.bufferSizeMB = 16;
P.stackSizeMB = 1024;
P.useROI = false;
P.roiX0 = 0;
P.roiY0 = 0;
P.roiX1 = 0;
P.roiY1 = 0;
P.useCache = true;
P.evaluateNoise = true;
P.mrsMinDataFraction = 0.010;
P.noGUIMessages = true;
P.useFileThreads = true;
P.fileThreadOverload = 1.00;


Once you have this script, it can be executed within a PixInsight shell script (SCP). This script will run the JS and then save the integrated image:

Code: [Select]
run -x "/home/vicent/ImageIntegration.js"
save integration -p=/home/vicent/integrated-image.xisf --nodialog --nomessages --noverify

This SCP can be automatically executed when you launch the PixInsight instance in each machine.

You need then a bash script that regenerates the JS for each machine with the specific settings to be tested.

Finally, you can execute the SCP on each machine with the following command:

Code: [Select]
PixInsight -n --no-startup-check-updates --no-startup-gui-messages --no-splash -r=/home/vicent/PI-shell-script.scp --force-exit
If you're executing this instance on multiple machines in an automated way, you'll need to specify the DISPLAY variable value in which the PixInsight should be run. Of course, you'll need a graphical session running in each machine.

Please let me know if you need any further info.
Best regards,

Hi Rick,

Wonderful. Did you use the spiral galaxy as white reference?

Best regards,

General / Re: Master Dark issues - vertical lines
« on: 2017 July 02 14:50:33 »

Could you please upload the set of the individual bias and dark frames?

Best regards,

General / Re: disk space ...
« on: 2017 June 22 07:20:33 »
Hi Mike,

Please could you share the model of the board? I would be interested to have something similar.


General / Re: disk space ...
« on: 2017 June 22 04:17:31 »

I have 10, 2 TB external disks for my data. Five of them at home, and five of them at my mother's home. Each pair of disks have the same data. That's my "personal cloud". ;-)

I store everything, from the raw to the master lights, and processing projects. That lets me a very quick access to any product, which has been very convenient to me in some moments. Of course, it's a lot of data... But those disks are cheap and you don't keep them running 24/7.

Best regards,

General / Re: disk space ...
« on: 2017 June 21 02:32:04 »

I would keep the registered and master folders. That will let you integrate new masters in the future without running everything again.

Best regards,

General / Re: Combining Two Different Nights
« on: 2017 June 18 12:01:24 »

It's important to apply this process through ImageIntegration and not through PixelMath. The reason is that ImageIntegration will measure the noise in both images and will weight both according to that measurement.

Also, please deactivate any pixel rejection, as it does not have any sense to apply it in this process.

This process is the same as the one to create a synthetic luminance. In that case, we simply integrate the master lights from each filter together.

Best regards,


I just wanted to show one experiment we did today with data by Rick Stevenson. We are really happy with the results, so I thought it's maybe worth to share it here. It's a very difficult example because there's literally a "highway" of satellites in the image. With the new large-scale pixel rejection we were able to completely reject all those trails with minimal noise increase.

Attached you'll find an animation without any rejection and with the large-scale pixel rejection.

Hope you like it!
Best regards,

General / Re: Globular Cluster colors . . .
« on: 2017 June 13 09:01:41 »
Juan was kind enough to let me play with an early release of 1.8.5.  Here's a comparison of "classic" ColorCalibration vs PhotometricColorCalibration for a couple of different white references (G2V and "average spiral galaxy").  There are also variants which correct for galactic dust extinction.  The target is the greatest of all globs, Omega Cen.

Kudos to Juan Conejero for the very ambitious and new-feature-rich 1.8.5 release, and to Vicent Peris for the PCC tool and the model for extinction correction. Thanks, guys!


Thank you Rick! Looking at your pictures, I see that PCC is running very well. :-) As listed by Simbad, the color index of Omega Cen without dust reddening is 0.64 magnitudes. To me, this value agrees perfectly with the results you're sharing: with G2V it should be white while it the spiral gal calibration should show it slightly bluish. :-) I think the merit of this precision is due to the linear fitting we have implemented in PCC. To me, the APASS catalog is very nice, provided that you're able to remove the possible outliers.

Best regards,

General / Re: Globular Cluster colors . . .
« on: 2017 June 13 08:43:49 »

I just made some research that can be very informative. I downloaded a catalog of globular clusters in M31:

In this catalog we have the Johnson B and V magnitudes plus the color excess due to dust reddening. Moreover, it has a flag indicating which clusters have been confirmed to be real clusters. So I filtered only the confirmed clusters which have the three magnitudes. Attached to this message is the histogram of the B-V color index distribution. The median B-V color index of this sample is 0.67 magnitudes, which is very close to a G2V star (0.66) and a bit redder than the generic spiral galaxy we have implemented in PCC (0.71). This means that, if we correct for galactic dust reddening, then the overall color of the average globular cluster should be close to white if we calibrate with a G2V star, or slightly bluish if we calibrate with a spiral galaxy.

On the other hand, you can see that there are a lot of globular clusters with very blue colors. Some of them even bluer than Vega!

By the way, in PhotometricColorCalibration you'll be able to correc the dust reddening imposed by the Milky Way for extragalactic objects. This means that we'll be able to look at those object as if we were shooting them outside the Milky Way. :-)

Best regards,

General / Re: Plate solve . Most accurarate plate solver ?
« on: 2017 June 10 05:25:32 »
Let me some time. I'll try to show the difference between distortion correction applied with polynomials and surface splines in some of my images. I'll try to solve one of my telephoto images with an earlier version of ImageSolver (where we used polynomials). You'll see that the difference is huge. I don't mean a sub-pixel difference. I mean an error in the range of 10 - 20 pixels in some cases.

Best regards,

General / Re: Plate solve . Most accurarate plate solver ?
« on: 2017 June 10 03:38:36 »
Hi Thomas,

Besides this discussion, the ImageSolver in PixInsight has a unique feature: it uses surface splines to correct for geometric distorsions. This is much more accurate than using polynomials or the standard WCS convention. I can show you some examples where it's impossible to correctly solve the astrometry by using polynomials, giving enormous errors at the corners.

Best regards,

General / Re: Blending Ha with Red...a new approach
« on: 2017 June 02 04:49:24 »

Please take a look at this thread:

I've been using the continuum subtraction method from 7 years ago. The continuum subtraction is not really my own idea since it has been widely used in professional astronomy from long time ago; what's mine is the idea of adding the continuum-cleaned H-alpha image to the color image. People coming to my intensive workshops since 2013 have a full example on this technique as part of the documentation. Some of my images have been developed using this technique:

To have an optimal result using this technique, you should take care of the below points:

- Always you add or subtract an image from another, don't subtract the sky level to avoid any clipping. That way it's also easier to check the result using STF. For instance, if you subtract the H-alpha image from the red, the equation would be R - Ha + med( Ha ). If you're multiplying the H-alpha image by a factor ("k"), then the equation is: R - ( Ha - med( ha ) ) * k.

- You are going to multiply the H-alpha image by a high number when you add it to the red channel. This also means that you're going to multiply the noise. So you'll always need to denoise the H-alpha image first.

- Even when you denoise the H-alpha image, it's difficult to get rid of the large-scale noise. There's no sense in enhancing the H-alpha image in the areas where you don't have H-alpha emission. So it's better to apply the H-alpha enhancement through a mask (built also from the cleaned H-alpha image) that selects just the H-alpha regions.

Even if there are multiple ways to integrate narrow and broad band images, I am currently teaching two techniques in my workshops. The first one, described here, works well when there's only H-alpha emission and it's applied to linear images. The second one preserves all the color information and it's applied to non-linear images. In the second case, the first technique produces terrible results as the nebulae become completely red with no different hues.

Best regards,

General / Re: Globular Cluster colors . . .
« on: 2017 May 31 07:49:01 »
And this is the result of calibrating with a G2V star with PCC:

Obviously, the color is biased towards the red. Each one has a different color rendition. The G2V version puts the balance on a "wihte" star according to our eyes. The spiral galaxy version put the colors of those stars in context, in the sense that a spiral galaxy has a significative contribution from all the different stellar populations; this means that, placing the balance point on those stellar populations, the globular cluster is not so red. I like more the spiral galaxy version since it shows properties related to the objects and not to our eye.

Best regards,

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