Une belle Varoise, cuvée 2022 (M83)

[Nathanael 6 875]

Superbe, bravo. Traitement top.

Nathanaël

[astrogatel 3 732]

Vu les conditions en France, c'est excellent. Elle me fait un peu penser à M74.

 

Nicolas

[COM423 13 648]

11 hours ago, Christophe H said:

Belle image, bravo.

Merci Christophe

 

9 hours ago, Nathanael said:

Superbe, bravo. Traitement top.

Merci à toi

 

4 hours ago, astrogatel said:

Vu les conditions en France, c'est excellent. Elle me fait un peu penser à M74.

C'est vrai que c'est plus une cible adaptée à des latitudes plus basses, mais en sélectionnant de façon drastique les nuits çà se tentait

Je pense qu'elle est plus brillante que M74 dont les spirales sont vraiment discrètes (?).

J'aime beaucoup cet objet, tout comme la galaxie du Sculpteur bien difficile elle aussi depuis la France mais on fait avec sa latitude

 

Très content que vous l'ayez appréciée vous aussi. Bonnes observations estivales !

 

Modifié 20 juillet 2022 par COM423

[christian_d 3 159]

Bonjour,

 

Jolie spirale avec un bon dosage des couleurs.

Sa déclinaison ne facilite pas sa capture. Bravo pour la persévérance et le total de poses cumulées.

 

Christian

[sebseacteam 12 402]

Le 19/07/2022 à 09:56, COM423 a dit :

bon j'ai de la lecture qui m'attends

Salut,

 

Des explications ici sur le fonctionnement du script GHS de Pixinsight.

A transposer à Siril.

J'ai appris des trucs  

 

https://remoteastrophotography.com/2022/04/generalized-hyperbolic-stretch-script-for-pixinsight-version-2-1

 

Extrait:

 

Using the GHS Script

I use the sample observation of Messier 51 in this section, so you can follow along if you like.

Start by opening all four files for the M51 observation using PixInsight.

Create the combined RGB image using the ChannelCombination process, and then close the R, G, and B images since we don’t need them anymore. Next, use the BackgroundNeutralization and ColorCalibration processes with their default settings to resolve the color image’s blue color cast.

You don’t need to do anything to the luminance image because it’s already aligned with the color image.

Start the GHS script (select Scripts – Utilities – GeneralizedHyperbolicStretch) – a large window opens on your PixInsight desktop.

The window has four primary sections:

At the top is the Histogram display where you’ll apply and evaluate your settings

Below the Histogram is the parameters section, where you make adjustments

To the right is the Preview window that shows you what your image looks like after applying the parameters you selected

At the bottom of the window are the Apply (green checkmark) button, close button (red X), undo/redo buttons, log window, preferences, documentation, GHS website link, and the reset button

The first thing you need to do is select the Target View, so you can set the image you’ll be working on. Select the M51_lum image. If you had applied the STF to the image, the script asks if you wish to remove the STF; answer Yes that you wish to remove the STF.

The preview image shows a very dark image and this is expected because the histogram function is at its default, which maps pixels one to one.

The first thing we’ll have to do is select the Symmetry Point (SP) value – this tells the script where to apply the stretch function.

Do the following:

Use the Zoom slider to zoom into the histogram until you’re able to see the spike in the histogram at about the halfway point in the histogram (for me the value is about 17). Your screen should look something like this:

 

Place your mouse pointer at the beginning of the rise of the histogram and click to place a blue marker line. Your screen should look something like this:




The green arrow points to approximately where to place the blue line, and the highlighted X value provides you with an idea of exactly where I placed the line. If you make a mistake, just click elsewhere to move the blue line. The blue line is just a readout value that sets the X and Y values below the histogram.
 

Note the value of X, highlighted in yellow on the preceding screenshot

Enter the value of X in the box labeled Symmetry Point (SP), shown in yellow in the following screenshot. Alternately, to copy the value from your selected point on the graph, click the Send value to SP button.



The Symmetry Point is the point where the stretch will occour. By placing the symmetry point near the beginning of the histogram, we are focusing our efforts on the most significant part of the image.  
 

Reset the Zoom back to the default of 1 by clicking the left-pointing arrow next to the Zoom bar below the histogram

Set the value of Local stretch intensity (b) to 8

The local stretch intensity defines how much stretch will be applied to the selected region. Higher values are more intense and lower values are gentler.
 

Drag the Stretch factor (ln(D+1)) to about 3.3 so that the spike in the histogram appears just beyond the 25% mark and the preview shows M51. This is what my screen looks like:


 

Click the green checkmark at the bottom of the window to commit the stretch to your image.

The preview image turns white because it is applying your selected stretch a second time. You can resolve this by clicking the Reset button at the bottom of the window.

Close the script window

The script asks if you wish to save your log before closing.

The log is a text file that saves the settings you used when the script was running. You could use this information later to repeat your steps, but for now, answer No to the question.
 

Next, create the color image by using ChannelCombination to combine the R, G, and B images. You may have already done this earlier so you can skip this step if you already have the combined RGB image.

The resulting image has a blue cast to it, which you can resolve by using the BackgroundNeutralization and ColorCalibration processes at their default settings. You’ll note that the background is uneven and you can improve that using AutomaticBackgroundExtractor at its default values, except for the correction method, which you set to Subtract; you can put checkmarks next to Discard background model and Replace target image.  
 

Note the name of the RGB image

Start the GHS script, select the color image from step 13, and remove the STF if you had applied it

Repeat steps 1-5 for the color image

The Symmetry Point (SP) is 0.00758, the Stretch factor for the color image is about 3.8, and the  Local stretch intensity (b) is 1.0

Click the green checkmark at the bottom of the window to commit the change

Reset the script so that the preview window is no longer white

Next, I’d like to improve the contrast around NGC 5195 (the upper galaxy of M51) to bring out the nebulosity a little more in the color image.

To improve the contrast, we need to find the approximate value of the pixels in the region. We do that by clicking the region in the preview window, which places a readout square where you clicked. The readout square is a little too large, so adjust its size to about 20 using the slider next to the Readout size or enter the value in the box.

In the big white box is the mean value of the pixel you selected. In my case, it is 0.30374 as shown in the following screenshot:




The pixel I have selected has a value of 0. 30374 (from the nebulosity in NGC 5195) – your number may differ, depending on where you clicked.

Click the Send value to SP button next to the number from the preceding step

Enter or select 1.0 in the Local stretch intensity (b) box

Slide the Stretch factor box to the right until you get to a value of about 1.7

The stretch is affecting pixel values around the 0.30374 value you found earlier and is adding contrast to just those pixels.

Click the green checkmark to commit the change to the image and then click the Reset button at the bottom of the script window

Next, we’ll improve the saturation of the color image to bring out more color.

Below the Histogram window, click the radio button next to Sat for saturation. Set the Stretch factor to 1.0 and note the increase in saturation.

Click the green checkmark to commit the change to the image and close the script window (answer No to Do you want to save your log before leaving)

Use the LRGBCombination process to blend in the M51_Lum image

The background is a little light, so we can use the HistogramTransformation process to clip the shadows. Do the following:

Open HistogramTransformation and select the combined image in the dropdown. Open the real-time preview and click the button shown in the following screenshot:



If your image is a little dark, reset the HT process and drag the dark point arrow (the one on the left), to the beginning of the hump on the histogram graph as shown:

 

Close the real-time preview and apply the HistogramTransformation process to the color image

Optionally, use the AutoIntegrate.js script to reduce noise in the image (under Extra Processing, select Noise reduction, set it to at least 5, and apply after selecting the combined image)

This is your final image – there is much more color in it and there’s contrast in the surrounding nebulosity around NGC 5195.

 

 

Le site de l'auteur du script: Mike Cranfield

 

 

https://ghsastro.co.uk/

 

 

tuto ici

https://www.dropbox.com/s/god5605o0luccbi/TAICSlides.pdf?dl=0

 

On retrouve les mêmes infos dans la version Siril, ça doit être applicable.

 

Pas fini de faire joujou avec des curseurs moi du coup  

[ALAING 59 456]

J'étais en train de répondre hier et . . . paf ! ! ! Panne d'internet

Je disais donc que pour m'y être frotté, ton image est magnifique

Bonne journée,

AG

[COM423 13 648]

@christian_d, @ALAING: merci beaucoup pour vos sympathiques retours

 

@sebseacteam: tu trouvais que je n'avais pas assez de lecture, tu m'en rajoutes

Trève de plaisanterie, un immense merci pour ces références, je potasse tout çà dès que la conjonction "temps libre" + "cerveau réactif" se présente

Modifié 20 juillet 2022 par COM423

[Lonelystar78 2 987]

Superbe prise

Bravo

 

Bon ciel

Patrick

[sebseacteam 12 402]

Il y a 21 heures, COM423 a dit :

tu trouvais que je n'avais pas assez de lecture, tu m'en rajoutes

J'ai potassé le tuto du GHS de pixinsight et j'ai appris des truc intéressants.

Il faut jouer avec l'histogramme pour connaître le point d'inflexion de l'image linéaire, noter la valeur, et la reporter dans le script Transformation hyperbolique, Point de Symétrie.

ça va concentrer la montée d'histogramme uniquement sur les valeurs de l'objet à révéler et pas au reste (bruit etc).

J'essaie de faire un mini tuto plus tard.

ça a l'air efficace en effet.

A suivre, ici ou sur post dédié

 

[airbus340 3 452]

Le 18/07/2022 à 23:47, COM423 a dit :

Voici donc le résultat de son observation acharnée sur 3 lunaisons consécutives (celles des 01 avril, 30 avril et 30 mai 2022) et 8 nuits :

Quelle superbe image ! Bravo 

La ténacité a payé !

 

Ph

[COM423 13 648]

Merci beaucoup @sebseacteam, je suis preneur du tuto si tu en fais un ! Pour l'instant, c'est le mystère total cette nouvelle fonction pour moi (j'ai repris les observations, pas trop le temps de me poser pour la lecture en ce moment...).

 

On 22/07/2022 at 8:36 PM, airbus340 said:

Quelle superbe image ! Bravo 

La ténacité a payé !

Merci beaucoup Ph. pour ton passage

Oui, sur cet objet j'étais très motivé, çà aide du coup mais côté turbulence j'ai été chanceux d'avoir les nuits qui allaient bien à la bonne période, car c'était vraiment la clef de la réussite à cette faible hauteur !

 

Bon ciel