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PixInsight => Gallery => Topic started by: Alejandro Tombolini on 2013 November 02 17:36:48

Title: NGC 253
Post by: Alejandro Tombolini on 2013 November 02 17:36:48
Hi, this is my try to NGC 253

Object: Sculptor Galaxy
Camera: Canon 5DIII - Filter Type I
Telescope: William Optics 132 FLT - Focal Lengl 925 mm -  f/7
Images: 47 x 5 minutos. ISO 1600
Total Time: 3 hours 55 minutes
Processing program: PixInsight
Comments: Guiding with Orion 100 and SSAG. From Trenel - La Pampa - Argentina

I couldn't have a good set of flats, so the integration was not as good as expected. Even can be seen a couple of dust spots.


In the processing I would try to highlight the fine luminosity that is seen in the periphery of the galaxy. See the area showed with previews.


First a crop using DynamicCrop


DynamicBackgroundExtraction placing the samples carefully, to avoid placing it over the stars or in the galaxy halo that I want to preserve


With AberrationInspector create a mosaic of 4 panels and use it as reference image in Background Neutralization Tool


Generate a new mosaic with AberrationInspector for using as Reference image of Background Reference and a preview that include the galaxy for using as Reference image of White Reference in ColorCalibration Tool


Open the DynamicPSF tool and generate the PSF to be used in Deconvolution. 


With star mask generate a mask to protect the core of the big stars when applying Deconvolution and to be used as Local support of Deringing


Apply Deconvolution to increase subtle details in the structure of the galaxy and make stars more puntuals


Apply the ScreenTransferFunction to the image by moving the blue triangle to the control bar of HistogramTransformation Tool


Build three masks to be used in different process. A range mask, an starmask and add both to have another to protect stars and background at the same time.


HDRMultiscaleTransform for increasing details in the galaxy


As the stretch was intensive transfering the Automatic STF to the HT, I am going to saturate also quite a lot to give color


The saturation generate noise in chrominance, that can be easily removed with ACDNR with a double mask, using rangemask to protect the background and the incorporated mask of the tool to protect the core of the galaxy that I want to continue saturated


SCNR to remove a greenish that has appeared, still protecting the background with the mask, as it look like nicer with green on it.


With ATrousWaveletTransform increase the contrast selecting Chrominance as target and modifying the Bias from layer of 16 pixels to 128


Extract L and use as mask protecting the galaxy and decrease the middle lights in the HT


Noise reduction using a range mask to protect the galaxy and slightly the background far from the galaxy. The main objective is the halo of the galaxy


A little contraste and Saturation with Curves Tool


Reduce the background bright protecting the galaxy with range mask and apply Gamma Stretch


Star reduction protecting background and galaxy with star mask and applying MorphologicalSelection 


Extract G channel and apply HDRMultiscaleTransform and HistogramTransformation. It is going to be used as mask in the following process


LocalHistogramEqualization protecting with G_channel


Increase contrast with InterChannel Curves using the Hue as Reference Channel and the CIE c as Target Channel


Decreasing the background a little more with Gamma Stretch


InterChannel Curves again to reduce the Cyan in the galaxy, protecting background and stars with Image56






Final image


Saludos, Alejandro. 
Title: Re: NGC 253
Post by: Zocky on 2013 November 02 17:50:30
Excellent image Alejandro, and even better tutorial.
Title: Re: NGC 253
Post by: marekc on 2013 November 02 21:44:09
Kudos, Alejandro! A beautiful image, a masterful workflow, and a fascinating tutorial. You've hit the Pixinsight trifecta!

- Marek
Title: Re: NGC 253
Post by: ajbarr on 2013 November 03 10:15:18
Fabulous and a very helpful work flow

Title: Re: NGC 253
Post by: cs_pixinsight on 2013 November 04 12:32:09
Alejandro, you are a master of the PI tools and getting the absolute most from your starting integration.  It's amazing this final processed image started with the first screen capture. 

Stunning image by the way.

Title: Re: NGC 253
Post by: marekc on 2013 November 04 12:35:47
Here's another lesson I learned from this tutorial:

If your filters and sensor window are fairly clean - not too many dust spots - and your object doesn't take up much of the frame, you don't really have to shoot flats. Well, you *should*, I mean do it if you can, but if not, it's not the end of the world. Cropping and DBE can deal with a lot of the problem.

This also reminds me that I really need to take my camera and filter wheel apart and get in there with a blower bulb. I have a lot of dust! Flats take care of the problem, but it would be nice to get at the *root* of the problem.

- Marek
Title: Re: NGC 253
Post by: ajbarr on 2013 November 04 12:36:24
It is amazing to me to see the evolution of a raw file to the finished product. People who are not into this hobby have no idea what we have to go through to end up with a beautiful image.

Title: Re: NGC 253
Post by: Eddy Timmermans on 2013 November 05 03:48:11
Simply stunning and very informative. Too bad not all tools are available to Windows users (InterChannelCurves i.e).
Especially amazing when you look at the original image.

Title: Re: NGC 253
Post by: Alejandro Tombolini on 2013 November 05 15:39:47
Thank you all for the comments, very motivating!!! :). As always I hope that the processing steps can be useful for whom are starting with PI.