Jump to content

Please rip this M82 apart .......

swag72

Recommended Posts

swag72

swag72

Posted
Posted

Here is the RGB of M82. I was expecting to add luminance and Ha as well. The luminance didn't work, and generally decreased the sharpness of the image, which I was surprised at. I've not even tried to add the Ha, as I have reached a point with this where I am hugely disapointed,

I have awful halo's on the stars that I just can't seem to avoid. Is it processing or data? I am using PI. I want star colour, but by trying to get some I am totally ruining the stars.

So anyone any suggestions and pointers? I am happy for you to totally rip this apart, I really need it.

The details are 15 x 300s in each channel and darks added as well. I know that's not a lot of RGB data, but I was hoping that the luminance would add to that - Sadly not!

post-18339-133877722731_thumb.jpg

Link to comment
Share on other sites
RobH

RobH

Posted
Posted

Although I have PI, I find it, so far, like trying to decipher klingon, so I can't help with anything platform specific.

If that was processed in PS, I'd say that the stars were suffering from too much saturation and would erase through the saturated layer to a layer where the saturation wasn't so heavy.

The galaxy however is looking fine, and there's a faint trace of the Ha dominated jets showing.

Rob.

Link to comment
Share on other sites
swag72

swag72

Posted
  • Author
Posted

Cheers folks - It's the star halo's that are my real issue. Whatever I seem to do, I get them like mad. I think that I need to work on my masks in PI - That is what is really letting me down.

I wish that it was easy to translate PS into PI!!!

Link to comment
Share on other sites
Euan

Euan

Posted
Posted

The halos could be from one of the RGB channels being slightly more out of focus? I had the same problem when I started doing RGB and I ended up going down the auto-focus route.

If if is that you should be able to tell in PI by comparing each colour by stepping through them on the R - G - B buttons to the left of the image window

Link to comment
Share on other sites
Euan

Euan

Posted
Posted
Sorry Euan, what am I looking at? I have the combined RGB linear image loaded - Not sure where to look or what to do from there ................

If you have the image open in PI there should be buttons down the left hand side, with the option to view either single colours or full RGB

EDIT: scrub that, I just noticed they don't open by default. Right click on the image then go to "display"

Link to comment
Share on other sites
steppenwolf

steppenwolf

Posted
Posted

Hi Sara,

I can't help you with the PI as I don't use it but the halos can be worked on in PS quite simply.

Duplicate the layer and apply Filter - Noise - Reduce Noise - Reduce Colour Noise (100%).

Now make the new layer a layer mask:- Layer - Layer Mask - Hide All

Using a suitably sized brush with white paint, brush out each of the stars with halos on them.

I also produced a false luminance channel from your image, sharpened it and placed it on top set to luminosity at 50% opacity to get rid of some artefacts the sharpening had produced. I flattened the layers duplicated the result, set the duplicate to LAB mode and increased the contrast of the 'a' channel (this boosts the red). I finally pasted the LAB image on top of the RGB image, made it a layer mask (hide all set) and painted in the red jets using the white paint brush again.

All that said, it may not be to your taste of course but the halos are improved and that was the main issue - apart from the halos, I loved your original image to be honest!

post-13675-133877722852_thumb.jpg

Link to comment
Share on other sites
steppenwolf

steppenwolf

Posted
Posted

You could try a lesser percentage of colour noise reduction - you'll see the result straight away but remember that it will also have some desaturation effect on the colours within the galaxy so you will still need to do the layer mask steps.

One day I will give PI a try but as I'm struggling to get data with the current weather conditions, new software is not the highest priority although I do believe it to be good.

Link to comment
Share on other sites
Space Bat

Space Bat

Posted
Posted

As mentioned earlier - perhaps use when stretching use preview window and do each individual channel separately - this will help in reducing over colouring some channels - colour calibration should also be used to bring out the best of your individual channels - did you use masks in processing??

Link to comment
Share on other sites
AndyUK

AndyUK

Posted
Posted

I think you're being a little harsh on yourself here... especially with the rework - The colour within M82 itself looks great to my tired old eyes, and I'd certainly be very happy with it!

Now, how about adding in that Ha you mentioned...? Go on - Have a go... even if it's only into the red channel! :icon_salut:

Link to comment
Share on other sites
swag72

swag72

Posted
  • Author
Posted

I tried the halo reduction script in PI and there seemed little success. I did use a mask, but I think that part of the problem is that my mask making is pretty poor!

@spacebat - Are you suggesting that I stretch each channel seperately prior to combining into an RGB image?

@Andy - Tried adding the Ha - Made not a scrap of difference - Must have added it wrong!! Ho hum, try again!!!

Link to comment
Share on other sites
AndyUK

AndyUK

Posted
Posted
@Andy - Tried adding the Ha - Made not a scrap of difference - Must have added it wrong!! Ho hum, try again!!!
I've never tried taking Ha of M82, but I just presumed that there would be SOME Ha data coming out of the centre and that additional Ha data would highlight this if added into the red channel... Obviously I'm incorrect.

I don't think there's much you can do to add it incorrectly - I think I read somewhere that Ha can be added into the Luminance 100% and then a %age added into the red channel... (Don't take my word for that though - I could be totally wrong... Yet again :icon_salut:)

Link to comment
Share on other sites
Space Bat

Space Bat

Posted
Posted

yes I have had some good results doing this...but like everything in PI its very much trial and error...

Don't overstretch just enough to bring out enough elements each channel brings...

But as others have said and so will I - it is still a damn good image....it is too easy to look at others and wonder why you haven't replicated it....your results with time will get better and better :icon_salut:

Link to comment
Share on other sites
swag72

swag72

Posted
  • Author
Posted

Thanks all - I think I need to get over my obsession with star colour and over saturate them, then my halo's wouldn't be half as bad I'm sure! For those using PI Juan has posted a good step by step guide in creating a good star mask here

Link to comment
Share on other sites

Archived

This topic is now archived and is closed to further replies.

Go to topic listing

  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue. By using this site, you agree to our Terms of Use.