M33 - Canon EOS 350D - 5h30 and a lot of PI Standard Beta 3

[Luc Coiffier]

Hi All,

This time I tried to use every trick I can to post-process this image.

It is a 309 light frames stack of various exposure time between 60 and 180 seconds at ISO 800.

Technical data:
Location: St Martin d'Uriage (France)
Altitude: 850 m
Date: August 22nd and October 15, 16, 24 and 26.
Telescope: Skywatcher 10" on EQ6 (mod Rajiva)
DSLR: Canon EOS 350D Baader mod

Pre-processing: DeepSkyStacker 2.5.4 (http://deepskystacker.free.fr)
Dark frames subtraction, Flat frames application, registering and kappa-sigma clipping stacking.

Post-processing: PixInsight Standard Beta 3
This time I tried not to kill everything so I took my time.

Luminance extraction (easy, one command  :wink: ).
Large scale and small scale details extraction using wavelets
Large scale and small scale details enhancement using wavelets, curve adjustments, masks...
Then the stars: it was my nightmare before now I am using the MorphologyTransform tool with the Morphological Selection and an amount of around 0.5, a selection value of 0.1 and 2 iterations in combination with a star mask to protect the rest of the image.

Then using the LRGBCombination it is a breeze to use the processed Luminance to the color image and voilà.

It is a 30% crop.


The full size image is here http://deepskystacker.free.fr/Gallery/M33_2006_Full.jpg (warning: 4Mb JPEG file).

It's still not perfect (I am not Hubble), but I am quite happy with the result  .

Hope you like it,
Luc

[Juan Conejero]

Hi Luc,

It seems that DeepSkyStacker and PixInsight form a good combo, doesn't it?  :lol:

I like this image very much. Let me make a couple of suggestions though. This image in my opinion would benefit from some careful noise reduction on low SNR areas, as the outer arms of M33. Noise is barely visible on the reduced version that you have posted here, but it is clearly present on the full-size image, on both the luminance and the chrominance. Of course, I wouldn't touch the central regions —this involves a mask. The new ACDNR process is the tool of choice. It is able to generate a luminance mask on the fly, and you can adjust it easily with the real-time preview interface (use the preview option on the Luminance Mask sectionof ACDNR's interface).

Finally, with respect to color balance, perhaps the image lacks a bit of green. But this is just a personal impression, and I can be wrong (I always reserve the right to be wrong, in fact  :wink: ).

Congratulations on a good work Luc. Keep it up.

[Luc Coiffier]

It seems that DeepSkyStacker and PixInsight form a good combo, doesn't it?  :lol:

Sure thing, and if I have had more time in the past few weeks it would be an even better combo. :wink:
More about that tomorrow

I like this image very much. Let me make a couple of suggestions though. This image in my opinion would benefit from some careful noise reduction on low SNR areas, as the outer arms of M33. Noise is barely visible on the reduced version that you have posted here, but it is clearly present on the full-size image, on both the luminance and the chrominance. Of course, I wouldn't touch the central regions —this involves a mask. The new ACDNR process is the tool of choice. It is able to generate a luminance mask on the fly, and you can adjust it easily with the real-time preview interface (use the preview option on the Luminance Mask sectionof ACDNR's interface).

I started the post processing with the previous beta version and did not want to switch when you announced the new one.
I will probably try the new ACDNR in a few days, after being able to look again at the image. Right now I can't stand it anymore :shock:

Finally, with respect to color balance, perhaps the image lacks a bit of green. But this is just a personal impression, and I can be wrong (I always reserve the right to be wrong, in fact  :wink: ).

That's always the problem with colors...taste and such.
The first color version was quite green and I didn't see it until I started to look at others M33 for reference.
Then I decided to make it less green and maybe I overextended the adjustment... just a tad.

See you,
Luc