Pixel rejection preference

[astropixel]

Hi All. Just a quick one. Looking at the images  below, is this a pixel rejection issue. Or, how might I better manage this over exposed areas.

6 x 10 sec, 6 x 20 sec 8 x 120 sec LRGB. plus 2 x 120 sec L.

many thanks

[DaveS]

The only way that I have successfully retained the Trapezium Area of M42, while also capturing the outer areas of the Nebula, is to take both long and short exposures, then combine them using 'Layers' in Photoshop.

The short exposures capture the Trapezium stars without burn-out, and the longer exposures, the outer gas and dust, but with a completely burned out Trapezium area.

When 'layer combined', the inner and outer areas blend nicely, giving a good overall image.

I don't yet know enough about PI, to know whether a similar method of combining long and short exposures is possible, but

hopefully, our resident experts will be able to enlighten us  

Dave

[Harry page]

Hi

I can not tell from the images if there is a pixel rejection problem , you would see this from the rejection maps 

However there is the HDR script which does construct a image from different exsposures

Loads of info here from lord Juan http://pixinsight.com/forum/index.php?topic=2320.0

Harry

[DaveS]

Thanks Harry, that looks interesting 

Have now downloaded and installed the 'tool'.

Dave

[astropixel]

Thanks Dave and Harry.

As you can see the results have come a long way - using HDRComposition.

I created separate integrated files for each image subset and then combined with HDRComposition - same for the Luminance channel.

That is - 10 sec R, G and B - integrate, define a linear RGBWorkingSpace and combine with ChannelCombination. Repeat for 20 sec and 120 sec subsets. Combine the 3 RGB images in HDRComposition.

Almost the same for L - integrate each subset 10, 20 and 120 second individually and combine with HDRComposition.

The screenshot rendition is a bit fuzzy, but the improvement is evident.

[DaveS]

That is indeed a significant improvement on what you had. 

Some further 'tweaking' needed I think, but none the less, a major step in the right direction.

Well done!!

Dave

[vicent_peris]

Hi!

I'm glad to see that the HDRC tool worked so well with your image.

Apply HDRWT to this image to flatten the core. Then a bit of color saturation. This is very important to check if it really went fine.


Regards,
Vicent.

[astropixel]

Thanks Vicent and Dave. I followed your suggestions but seem to have removed the four stars in the centre, attempting to reduce the brightness.

I extracted the luminance, applied ATWT to blur the image and reduced with HT, and then subtracted from the LRGB image with PixelMath. That fixed the brightness but removed the central stars.

What do you think - this has been quite a demanding subject and I am learning a lot, but can't quite find my way around resolving the luminosity and retaining detail - where am I going wrong?

Is it that I am attempting to increase the nebulosity, whereas the image really needs more data, and this is over saturating the core?

[astropixel]

10 minutes later.

This time I duplicated the image and reduced its luminosity with HT. Added the clone from the main image and readjusted the brightness with HT.

This is the best that I can do at this stage - where do I need to go from here?