NGC6302--Butterfly (aka Bug) Nebula

[Geoff]

http://www.astrobin.com/104993/C/
The core of this object was surprisingly bright at 10 min subframes.  Reduction to 200 second subframes resolved this issue. Two separate images were processed and then combined with HDRComposition. Processing was quite standard for both images:

• ChannelCombination to produce a linear RGB image, followed by DBE and ColorCalibration.
• DBE and deconvolution on the luminance
• Combine L and RGB to produce a linear LRGB image
• Masked stretch
• HDRComposition
• Play around with Curves (for saturation), Histogram, TVG denoise
• Apply HDRMultiscaleTransform to the composite image with stars protected by a mask (thanks to Cosmick for suggesting this)
• Minor cosmetic changes

Geoff

[vicent_peris]

Hi Geoff,

Nice image. HDRC was designed to work with linear images, not with processed ones. As you say, you first processed the images. Could I see them separately? Maybe the stars are not very good (see that all of them have a kind of "separate cores") due to this workflow.


Thanks,
Vicent.

[lucchett]

Hi Geoff,
Could you also detail how do you build a linear LRGB?
Are you using the LRGB combine tool?
Thanks, andrea

[Geoff]

Hi Geoff,

 As you say, you first processed the images. Could I see them separately?

Thanks,
Vicent.

Thanks Vicent.  The files have been uploaded to Endor:

1. Linear_200sec subs
http://endor.uv.es/files/data/public/165c44.php

2. Linear_600sec subs
http://endor.uv.es/files/data/public/a62251.php

3. RGB_200sec subs
http://endor.uv.es/files/data/public/138b8b.php

4. RGB_600sec subs
http://endor.uv.es/files/data/public/4c67a5.php

The only processes applied have been image calibration and registration.  Each luminance has been registered to its corresponding RGB image, but the short exposures have not been registered to the long exposures.
Regards
Geoff

[Geoff]

Hi Geoff,
Could you also detail how do you build a linear LRGB?
Are you using the LRGB combine tool?
Thanks, andrea

Hi Andrea

• First combine the RGB images using the ChannelCombination tool with the radio button RGB checked
• Then open the ChannelExtraction process and check the CIE L*a*b* radio button.  Apply to the RGB image generated in step1. This will generate a luminance image (which you will discard) and two images for colour.
• Go back to the ChannelCombination tool and click the CIE L*a*b* button.  Use the _a and _b colour images from step 2, but replace the discarded luminance generated in step 2 by your luminance.  Hit the apply button and you will generate the linear LRGB image.

Regards
Geoff