Getting the star colours to show up ?

[boris sputnik]

Can someone help me bring out the colours of the stars when I process ? Where in the process and what tools should I use ?
Anyone have an idea !
Thank you !
Maxx

[DMouse]

Hi, use a star mask to protect the back round and then use Curves to ramp up the Saturation in the stars. This will stop the background from getting messy.

Clear Skies

Paul

[boris sputnik]

Hi, use a star mask to protect the back round and then use Curves to ramp up the Saturation in the stars. This will stop the background from getting messy.

Clear Skies

Paul

Thank you Paul ,I will try that...but the galaxy will not get protection either

[vicent_peris]

Hi,

Here in my article you'll find some useful information:

http://pixinsight.com/tutorials/NGC7023-HDR/en.html


Regards,
Vicent.

[boris sputnik]

Hi,

Here in my article you'll find some useful information:

http://pixinsight.com/tutorials/NGC7023-HDR/en.html


Regards,
Vicent.

Thank you very much Vincent !

[Warhen]

Dosvedonia Boris, One 'trick' for star color is not to lose it in the first place. Be sure that stretches don't saturate (as in clip) highlights. The MaskedStretchScript is fabulous for this. Certainly, as stated, star saturation can be later enhanced in a couple of ways, generally Curves/Saturation or ColorSaturation with a mask.

[Tom OD]

That's a good tutorial Vincent, but I was wondering how do you know the median value of the HDR image was 0.43 that you then used in the Masked stretch script?
Thanks Tom

[Bob Andersson]

Hi Tom,

I developed my "Repaired HSV Separation Script", discussed in this thread, to help with this. If the script isn't already part of your PI install then that thread also includes a download link.

Bob.

[Tom OD]

Thanks Bob I'll look that up. I
Tonight I spent some time practising this but I didn't get some good results. I have 2 more questions. Based on the following quote from the tutorial
"This process must be masked with the mask we have built in the preceding paragraphs. This mask has very low pixel values (0.1 to 0.2 on the star edges), so we can apply the same PixelMath instance iteratively to control the intensity of the process"
1) Do I use the mask on all 3 images that are used in the Pixel math formula to join the masked stretch to the HDR LS image, or just one or 2 of them?
2) How do you do the pixel math 5 times. Do you swap the new image into the pixel math formula?
Thanks Tom.

[Tom OD]

I've ended up back at practising the Masked Stretch script, and I have also ended up with the same issues and questions. I 'm attaching a screen shot showing that I have got to the steps as shown in the tutorial, but the resulting Pixel math formula image has blurry large scale details.
So do I use the mask in all 3 images, or just the MS version?  In the screen shot I have used the mask on the MS image, and I have it protecting the stars, they are red. I thought this would allow the unprotected area to get substituted with the HDR stretch.
Any ideas anyone?
Thanks Tom

[Phil Leigh]

You need to be careful with the Masked Stretch script - it doesn't always mask the larger stars correctly - you will need to play with its masking parameters on some images. A classic sign is that larger stars end up with red centres surrounded by a white halo.