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Topics - vicent_peris

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1
New Scripts and Modules / Pattern subtraction scripts
« on: 2019 May 06 04:03:40 »
Hi all,

I'm working on a new image, but the CCD camera is getting very old, so it has a sensor plenty of defects. To remove these defects I had to write some scripts. I'll be writing an online article about the scripts in early June. The scripts don't have a GUI at this moment (and I have no plan to add it, I simply don't have the time). So anybody is welcome to code it. :-)

The attached image shows an integration of all the H-alpha exposure without alignment. This image increases the signal to noise ratio of all the defects in the image, which are the following:

- The top and bottom dark bands are some sort of gradients introduced (I guess) by the amplifier. These gradients vary in intensity from frame to frame.

- The diagonal dark structure at right bottom is an RBI residual coming from the flats on the afternoon. This planetary nebula has an extremely low surface brightness, and shooting with RBI supression would increase the background noise, so always do a regular readout. The problem is that you can have an RBI residual of varying intensity in certain frames.

- The CCD has a lot of entire and partial defective columns. More of 10% of the columns are now defective, which means that you cannot use CosmeticCorrection because you would be painting a lot of data...

These are the scripts I've developed:

PatternSubtraction script:

Script to subtract a fixed pattern from an image. This script can correct the active image or a list of images in an specified input directory.

To correct the RBI residual signal, I made a master dark with RBI-cancellation readout. Then, you remove the small-scale components with MMT. This image will work as the pattern reference. The script can be applied to the active image or a list of images in an input directory. In any case, you need to open the processed pattern reference image and specify its identifier in the script setup. The script works by progressively subtracting the pattern from the image until it finds a minimum in the noise measurement. I'm also attaching the RBI pattern reference image.

LinearDefectDetection script:

Script to detect defective columns or rows in a reference image. It can detect entire or partial defective columns or rows. The best approach to detect these line defects is to use an integrated image of non-aligned images. This way, we increase the signal to noise ratio of the lines, which is crucial to be able to detect them above the noise floor. This wouldn't be possible in a single subframe because most of the defects are well below the noise of the image and they only appear as diffuse lines in the integrated image. So, first you need to generate this kind of master image. The script will be always applied to the active image. It takes its time to finish since the algorithms are complex, but the time is well worth and it's a one-time process.

PartialLineDetection script:

A stand-alone version of the partial line detection function. It's always applied to the active image, which should be an integrated image of the subframes without alignment, in the same way as in the LinearDefectDetection script. It writes a CosmeticCorrection-compatible defect table as well.

LinearPatternSubtraction script:

Script to correct residual column or row patterns in an image. It can read the previously generated defect table and correct the defects on the active image or in an image list. It is possible to correct all the entire columns or rows in an image and, at the same time, correct the specified defects in the defect table.



The script writes a CosmeticCorrection-compatible defect table to disk. You can then use this table in CosmeticCorrection, but it better (IMHO) if you use this table to correct the defects with LinearPatternSubtraction.

All these scripts are configured by modifying the properties of the Config function. If you want to give it a quick try, open the LinearPatternSubtraction script in the script editor. Set the correctEntireImage property to true, don't specify a defect list in the partialDefectsFilePath property, and modify the backgroundReferenceLeft, backgroundReferenceRight, backgroundReferenceTop and backgroundReferenceBottom properties to select the right area in your image. Then, hit F9 to apply the script to the active image. It will correct and vertical banding in your image.

The scripts I'm sharing solve all the problems above. Feel free to contribute. I guess my code won't be very smart since this is my first time programming in an object-oriented language (my only experience up to now was shell scripting). But the code is very well commented and documented. PLEASE READ THE INCLUDED DOCUMENTATION!

Feel free to ask anything about the scripts and how to set them up.


Thanks,
Vicent.

2
Hi,

I just wrote an article with Juan about the new PhotometricColorCalibration tool. You can read it following the link below:

https://pixinsight.com/tutorials/PCC/index.html

The article is focused on our philosophy of color and how it is applied in the tool, along with a description of the specific features of PCC. Finally we give some usage advices for you to apply correctly the tool and to help you to solve any possible pitfall.

We hope this article will be helpful for you.
Enjoy!
Vicent.


3
Hi,

People coming to my workshops already know that we were working on an important update to the ImageIntegration tool to allow a better rejection of meteors and other "track-like" outliers. Well, I'm happy to announce that we finally finished the development of this improvement to this critical tool. I post here some examples.

Below you can see a comparison between the regular integration and the integration with the new improved tool. It's a 15 frame integration using Linear Fit Clipping with the same settings in both cases. This data set has originally 75 frames, but I manually selected all the frames where there was a meteor:




Image provided by Frank Willburn.

This update is able to handle the rejection of big planes:



And perfectly reject RBI artifacts:



Below you can see the comparison between the current version of ImageIntegration and the new one coming in a few weeks:




Image provided by Frank Willburn.
This new feature also helps rejecting stars in a comet-aligned image set:




Of course, the rejection of the stars depend greatly on the speed of the comet and the optical system, but will be always better than in the current version of the tool.

One advantage of this new feature is that it is a completely automated solution, so it doesn't require any manual rejection of image bands. We hope you'll like this tool and the new ones that are coming in PixInsight 1.8.5. As always, our goal is to provide you a state-of-the-art solution for your imaging.


Best regards,
Vicent.

4
Hi,

Today we updated the HDRComposition tool with a new functionality that adapts the composition images to produce a seamless result in specially difficult cases. The main parameter, Replace large scales, performs a large-scale adaptation between the images; this way, the shorter exposure is placed over the large structures of the longer exposure. This adaptation is specially useful to correct bloomings. Below you can look at the effect of this parameter:

Without large-scale adaptation:


With large-scale adaptation:


Two crops at original size:



This HDR composition is the result of three master images with an exposure of 300, 60 and 10 seconds. The images are proprietary to Leo Bette.

This kind of composition problems come from two sources:

- The limitation in the scaling precision imposed by the high noise level of the shorter exposures.
- The residual image gradients, specially if they are different in the short and long exposures.

This new parameter tries to adapt the composition at a local level to achieve a seamless composition in these difficult cases. We use the multiscale median transform to transfer the large scales from the long-exposure image to the short one. The Replace large scales parameter sets how to split the images between small and large-scale components. By setting it to zero we simply disable this technique. A higher-than-zero value sets the number of multiscale layers to be removed to generate the large-scale image components. Because it does not make any sense to have a small value in this parameter, the current parameter value equals to that value plus 4. This means that, for a value of 2, we'll remove the first 6 layers to generate the large-scale images.

To work properly, we should be able to completely remove the saturated areas in the large-scale images. Here you have the large-scale images generated with MultiscaleMedianTransform by removing 4, 5 and 6 layers (remember that the parameter will have always a value of n - 4):



The large-scale images should have no traces of the saturated areas to avoid any artifact. When working with your images, you can check how many layers you need to remove by loading the image with bloomings and generating a large-scale image by disabling the first n layers in MultiscaleMedianTransform. For this composition we removed 6 layers, so we set the Replace large scales parameter to 2. Please note that this is very important; leaving the saturated structures in the large-scale images will generate artifacts in the composition. These are the settings of HDRComposition for this image:



A common problem with this kind of composition is the noise in the shorter exposures. Please keep in mind that you won't be able to have a good composition if your short-exposure master has a very short total exposure time, since its noise will be much stronger than the long-exposure master.

Noise was a problem for this image as well, so a denoising process was needed over the blooming areas. I recommend to activate the Output composition masks check box to use the composition masks in the denoising process. For this image, the denoising consists of a MultiscaleMedianTransform process followed by a MorphologicalTransformation process; these are the settings of both tools:



Below you have a side comparison between the original composition and the composition after denoising:



This technique requires more exposure time since we need to acquire short-exposure subframes, but the resulting composition has no painting at all and recovers the true information behind the bloomings. For instance, in the image above, we reconstruct the large scale components of the dark nebulae in the composed image. We recover some faint stars as well, as seen below:




Aside from this new parameter, please note that as a general rule for blooming correction we'll need:

- To increase the Mask growth parameter to grow the composition mask, since the bloomings usually have non-saturated (or even dark) edges.

- We'll always need to smooth the composition mask since the composition never will be absolutely perfect.



Hope you'll enjoy this new feature.
Best regards,
Vicent.

5
Gallery / NGC7217 from Calar Alto Observatory
« on: 2016 October 14 15:55:55 »
Hi,

Here you have an image of NGC7217 in Pegasus from my astrophotography project at Calar Alto Observatory. It's an H-alpha/RGB composite made with the 1.23 meter telescope. The total exposure time is 19 hours with a 4Kx4K CCD camera. Here is the image:



And here at full resolution:

http://astrofoto.es/astrofoto/foros/NGC7217.jpg

Here you can see the isolated H-alpha emission:



This image was created with some of the techniques I teach in my intensive workshops to blend the narrow and broad band emissions.


Best regards,
Vicent.

6
Gallery / NGC4435-4438 from Calar Alto Observatory
« on: 2016 October 14 15:52:11 »
Hi,

Here you have an image of the NGC4435-4438 galaxy pair in the Virgo Cluster from my astrophotography project at Calar Alto Observatory. It's a H-alpha/RGB composite made with the 1.23 meter telescope. The RGB data comes from data acquired with two different cameras with 2Kx2K and 4Kx4K CCD sensors with a total exposure time of 14 hours. The narrowband data was acquired with the 2Kx2K camera with a total exposure time of 20 hours. Here is the image:



And here at full resolution:

http://astrofoto.es/astrofoto/foros/NGC4435-4438.jpg

This image shows the H-alpha structure that links these galaxies with M86. The only photo recording this structure was acquired with a 4-meter telescope and is aesthetically horrible.

Here you can see the isolated H-alpha emission:



This image was created with some of the techniques I teach in my intensive workshops to blend the narrow and broad band emissions.


Best regards,
Vicent.

7
Gallery / IC2574 from Calar Alto Observatory
« on: 2016 October 14 15:43:44 »
Hi,

I'm finishing some pending works from my astrophotography project at Calar Alto Observatory. This is the first one, IC2574, an irregular galaxy belonging to the M81 group, in RGB and H-alpha:



And here at full resolution:

http://astrofoto.es/astrofoto/foros/IC2574.jpg

It has 12 hour exposure time with the 1.23 meter telescope and the 2Kx2K camera.


Best regards,
Vicent.

8
Hi,

I'm glad to announce two combined beginner/intensive PixInsight workshops that will take place in San Jose, California, USA, from December 2 to 7 and 9 to 14, 2016.

These workshops start on Friday, offering a combined beginner/intensive weekend. The intensive workshops continue on Monday through Wednesday. These combined workshops will offer the user a more flexible opportunity to learn image processing. On the weekend an introductory workshop to PixInsight and the basic image processing techniques will be offered for up to 20 people. The following three days of each week will review more advanced techniques in a fully personalized learning experience for up to 12 people.

You can register either for one of the weekend workshops, or for one of the full 6-day workshops. For more information, please visit the workshop's webpage:

https://pixinsight.com/workshops/sanjose-2016/

The beginner workshop will introduce you to the PixInsight platform and the basic image processing techniques applied to astrophotography. You'll benefit from this workshop even if you have very little experience with PixInsight because we'll start from scratch on the software usage on Friday afternoon. The topics covered during the weekend will be:

    - The graphical user interface.
    - LRGB.
    - Denoising with TGVDenoise.
    - Dynamic range management techniques.
    - Hubble's palette.
    - Start-to-finish example.

The intensive workshop will be an in-depth review of more advanced techniques, as well as a longer start-to-finish example. The most interesting part of this workshop is when everyone works with his or her own images. In this way, people learn how to apply the just-learned techniques to their own photos. Everyone will be guided in the particular processing steps to achieve an optimal result. The topics covered in this part will be:

    - Narrowband / broadband composition techniques.
    - Three additional start-to-finish examples.
    - Multiscale tools applied to star masking and sharpening techniques.

Please note that, although the topics in the Intensive part are more advanced, they are also part of what I consider the full set of beginner techniques. Intermediate Intensive workshops will begin in the near future.

This workshop is sponsored by Pleiades Astrophoto and the Astronomical Observatory of the University of Valencia.


Best regards,
Vicent.

9
Hi,

I'm glad to announce a PixInsight Weekend workshop that will take place in Vienna, Austria, from September 16 to 18. This Weekend workshop is limited to 25 people, I'm no longer offering this kind of workshops for up to 40 people. This way you can have a more personalized learning experience.

If you want to register please follow this link:

https://pixinsight.com/workshops/vienna-2016/

The workshop is divided in two levels in order to fulfill the needs of the attendance:

- Beginner level (Friday afternoon / Saturday morning):

    - Introduction to the graphical user interface.
    - The LRGB workflow.
    - Gradient correction.

- Intermediate level (Saturday afternoon):

    - Dynamic range management.
    - Image delinearization.

Please not that this is the first time I teach topics of intermediate level in a workshop. Don't expect to simply learn how to apply HDRMT and histograms to your image. These topics will be part of the upcoming intermediate level Intensive workshops (still to be released).

On Sunday we'll review a full example, starting with data set analysis and inspection, going through the data set preprocessing and postprocessing to the final image.

This workshop is sponsored by Teleskop Austria, Pleiades Astrophoto and the Astronomical Observatory of the University of Valencia.


Best regards,
Vicent.

10
Hi,

I'm glad to announce three PixInsight workshops that will take place at the Tanque Verde Ranch in Tucson, Arizona, USA, from May 6 to 12 and May 16 to 22.

Starting on May 6th, the first workshop will be a combined beginner/intensive like the one we offered in 2015. This combined workshop will offer the user a more flexible opportunity to learn image processing. On the weekend an introductory workshop to PixInsight and the basic image processing techniques will be offered for up to 40 people. Following this workshop, a 5-day intensive workshop will review more advanced techniques in a fully personalized learning experience for up to 12 people. In order to fulfill the high demand of the last year, we are also offering a second intensive workshop on the following week, from May 16 to 22.

We have already sold 75% of the seats for the intensive workshops, so register as soon as possible if you're intested in attending. You can visit the workshop webpage for detailed info:

https://pixinsight.com/workshops/tucson-201605/

Here you can see some photos of the 2015 event:

Starizona and Software Bisque were sponsoring the event:




Two views of the weekend workshop:




BBQ for Saturday dinner:


And an observing session at night with telescopes from Starizona and Software Bisque:




Two photos of the Intensive workshop:





These workshops are being sponsored by Pleiades Astrophoto and the Astronomical Observatory of the University of Valencia. We want to publicly thank Bob Rieger for his help on the organization; we are making these workshops reality thanks to his collaboration.


Best regards,
Vicent.

11
Gallery / Total lunar eclipse, 2015-09-28
« on: 2015 October 01 08:50:17 »
Hi,

I took some pictures of the lunar eclipse. Most of them are close ups with a 20" Planewave telescope. The last picture was made with a Nikon 180 mm f2.8 lens. All the pictures were shoot with a mirrorles Panasonic GX-1 camera.

The blue light transmitted by the ozone in the high stratosphere:

Bigger here.

Just before totality (2-panel mosaic):

Bigger here.

Tycho area:

Bigger here.

A star rising behind the Moon:

Bigger here.

A wider view of the totality over a star field:

Bigger here.


Hope you like it!
Best regards,
Vicent.

12
Workshops and Conferences / Workshops Postponed to 2016
« on: 2015 September 30 15:06:40 »
Hi,

During the next months I won't be able to give my workshops. This is because my first daughter was born one month ago, and also because I'm preparing a new teaching project that's needed to enhance the learning experience in my workshops. At this moment I'm not able to give workshops that require a lot of preparation (like the weekend workshops) or traveling around the world. The only exception will be an intensive workshop here in Valencia by the start of December (to be published in a few days) because it's a 20 minute drive from my home.

I'll start my regular activity next spring. The next EPIC and Harvard workshops will be on 2016 as well. Stay tuned because we'll be asking for user presentations / speakings on these meetings.


Sorry for the inconvenience, but I really think it will be worth the wait.
Best regards,
Vicent.

13
Hi all,

I'm glad to announce a PixInsight workshop that will take place at the Tanque Verde Ranch in Tucson, Arizona, USA, on June 5th to 10th.

This is a newly designed, 6-day long combined workshop that will give the user a more flexible opportunity to learn image processing. On the weekend an introductory workshop to PixInsight and the basic image processing techniques will be offered for up to 40 people. Following this workshop, a 3-day intensive workshop will review more advanced techniques in a fully personalized learning experience for up to 12 people.

As all my other workshops, this workshop has been conceived with a special focus on the active participation of the attendees. Each registered participant will be provided with a personal account on our file servers, where he or she will be able to upload raw data that will be worked out during the workshop. On Sunday we will review a start-to-finish example based on user data, so it is strongly recommended to upload full data sets.

The intensive workshop will be an in-depth review of some more advanced techniques, as well as a longer start-to-finish example. The most interesting part of this workshop is when everyone works with his/her own images. This way, people learn how to apply the recently learnt techniques to their own photos. I will guide everyone in the particular processing steps to achieve an optimal result.

The topics covered will be, among others, the graphical user interface, elementary techniques of astronomical image processing, image delinearization and dynamic range compression, and narrowband imaging.

You can register only on the weekend workshop or the full 6-day workshop. For more information visit the below webpage:

https://pixinsight.com/workshops/tucson-2015

This workshop is being sponsored by the Astronomical Observatory of the University of Valencia. I want to publicly thank Bob Rieger for their help on the organization, we're making this workshop reality thanks to his collaboration.


See you in Tucson!
Vicent.

14
Gallery / Pleiades widefield
« on: 2015 March 06 15:47:16 »
Hi!

This is my latest work. It has been done at the observatory where I work, the Observatory of Aras de los Olmos. We just formed a small astrophotography group there, so this is a collaboration with some other people.



Image credits: OAUV, Vicent Peris, Òscar Brevià, Pepe Bosch, Satur Martínez, Salvador Moros, Alejandro Vera.

You can watch the full resolution version here. It has been shoot with a FLI Proline 16803 and LRGB filters through a Nikon 180 mm f2.8 lens. It has about 14 hours exposure time. We had some problems with the stars because this is a new setup, so next time they will be much better.


Best regards,
Vicent.

15
Hi all,

We've announced this event by email but I forgot to announce it on the forum. So I'm posting this event now, specially because we still have one seat. This PixInsight intensive workshop will take place in Katonah, New York, USA, from March 11th to 17th, 2015.

This workshop aims at giving a comprehensive operational/technical understanding of PixInsight to a small group of participants (5-10) over the course of 7 concentrated working days. The workshop will take place in a mid-century modern, private home in Katonah, near New York city.

Participants will bring all their own unprocessed data sets which will be processed during the week. The structure of the seminar will allow participants an in-depth view of Pixinsight, with the goal of having a total immersion in the process of the image creation.

For more information about the workshop, please visit the dedicated webpage at pixinsight.com:

https://pixinsight.com/workshops/katonah-2015/

Due to its singular characteristics, we are limiting this workshop to 10 seats. We still have one seat.

This workshop is being sponsored by Pleiades Astrophoto and the Astronomical Observatory of the University of Valencia.


See you in Katonah!
Vicent.

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