NGC3372 - its not quite right?

[h0ughy]

the colour is terrible - much needed processing skills lacking. Taken Sat night (9april2011). 127ed cooled canon 40D iso800

made up of 1s, 5s, 15s, 30s,60s, 120s, 300s, and 605s totalling around 5.5hrs. that CLS filter is killing me with colour issues, but its better than the light pollution:help::shrug:


EDIT FINAL REPRO FOUND HERE (http://www.iceinspace.com.au/forum/attachment_browse.php?a=92299)

[jjjnettie]

Lots of nice detail there.
Be blowed if I can work out how to get rid of that blue background without severely clipping the image.
I'm interested to see what solution you're given Dave.

[h0ughy]

yes it is presenting itself a great challenge:rofl:

can i say my brain hurts;)

[Tandum]

Dave, I had one of those CLS filters and the colour cast drove me crazy as well. I had the clip in version and was able to shoot a custom white balance through a normal lens which solved the problem. I finally got an ldap filter which does not change colours.

[h0ughy]

got a link? and samples?

[Tandum]

Got it wrong, it's an IDAS LPS-P2 filter, from Hutech (http://www.sciencecenter.net/hutech/idas/lps.htm). No examples, haven't had a canon in a few years now.

[jjjnettie]

I had a quick play with the data Dave.
I set the black point in curves, choosing the background blues, then adjusted the yellows in Selective Colours.

[strongmanmike]

Looks ok enough to me :shrug:....sure you could play around a bit like JJJ has done but in the end it is already in the ball park so just comes down to what colour adjustments you think look best :thumbsup:

Mike

[h0ughy]

thanks Mike but I am disappointed with the result. I am expecting far too much from the setup. I would have thought that the combination of short and longer exposures would have netted me some star colour retention and maybe some better colour balance than it has. Almost makes one want to buy a mono camera and do narrowband?

[h0ughy]

thanks JJJ - was that from the file i sent you?:question:

[h0ughy]

Well for 5h 30m there should be a better image but the more I look into this the more I hate it. When guiding the rms was going from 0.17 through to 0.46 and I think the seeing wasn’t very good. I focused the stars like normal but with the soft seeing - well it’s more apparent in the data when processing it :sadeyes: - time wasted.

just had a play at lunch with a file - not liking it at all:sadeyes::(

[atalas]

Hough,like Mike said It still looks good dude! now,sometimes simple is best mate and especially for bright nebs...looks like too much contrast here,If you used DBE try not using It.

With color adjustments you'll find that slight adjustments have dramatic impact.

You've come a long way David so stop beating yourself up and enjoy and you'll smash It!

[h0ughy]

no not DBE - i used the HDR script then added other files via staralign. might retry doing it without the script:question:

[gregbradley]

Overall not a bad image but I can see why you are disappointed. Five and a half hours on a bright object is a big investment in time and energy.

I suggest you look at your basics here rather than fiddle with Photoshop tools. Some of those Photoshop tools are more remedies for problems with the imaging and are not a substitute for the gear being setup and working well.

In your case, following this thread, it seems that this filter you are using is causing all sorts of colour grief. So the custom colour balance suggestion sounds the best. If you are shooting in RAW mode you should be able to adjust that after the fact of shooting, if not then you are stuck with it. But taking a custom white balance shot is not hard and means the image that comes out of the camera is already well balanced requiring very little processing.

If you don't have one already - go to a Camera shop and get yourself an 18% grey card.

Then you shoot that at midday on a clear day with your filter on.

Then you set the menu for white balance to use that shot as the custom white balance. Its in the camera menus.

Now take a shot with your camera an notice the difference in the image it displays. It should be much closer to normal colour.

From what I have seen it appears this filter knocks down the reds and pumps up the magenta's causing a nasty and hard to correct imbalance.

Greg.

[h0ughy]

thanks for the constructive input Greg - well and truely taken on board. :thanx: here is a repro i have done from scratch. its not perfect but it has improved the colour a tad

[multiweb]

It's quite good data. Have you tried pixel maths for your color balance prior to recombining. I do a lot of that and it always gets me in the ball park especially when blending different panels. I use CCD Stack but I assume Pixinsight or other programs would have a similar function. The idea is to pick a dark area and measure the INT MODE (in CCD Stack) then add the offset from the highest ADU channel.

[h0ughy]

why midday?:shrug: willtry the 18%:question:

[h0ughy]

not thAt smart Marc:lol: only know a few things and not all that well. tutorial on how to do this would be good.

[multiweb]

Pretty simple really when you do it a couple of times. Measure the INT MODE in a dark part of your picture. In CCDStack you drag the mouse in a small dark area. That highlights the area (small square) and gives you a bunch of info about the underlying data. Let's say you end up with this:

RED 1282
GREEN 888
BLUE 613

You need to add 394 to the GREEN and 669 to the BLUE to get to 1282 in both (same as RED). Then you check your histogram and apply the same amount of stretching you have in the RED to the GREEN and BLUE. Then all you have to do is combine to color and that'll get you pretty close to start with.

[strongmanmike]

Don't know if it is necessarily more accurate but I like this colour scheme, close to Malins famous keyhole colouring :thumbsup:

Mike

[gregbradley]

I think the idea of midday so the light is at its brightest and most white. Later in the afternoon or morning light is not quite white and can be a bit reddish/pinkish depending on the time of course.

The least amount of atmosphere,pollution the light has to go through would be at midday.

Greg.

[gregbradley]

Yep, that looks closer to the mark.
I think a bit more blue should be present in Eta. It has a bluish tinge in parts of it.

Greg.

[multiweb]

David, this (http://www.iceinspace.com.au/forum/showpost.php?p=382253&postcount=1)is an old post but it might get you started.

[h0ughy]

ok thats a fair comment

[h0ughy]

do you have an example Greg?

[h0ughy]

thanks Marc

[gregbradley]

Here is one of my better Eta images using an AP140 and Apogee U16M. Not saying this is perfect
but it is one of the better ones I have taken. More close up images tend to look a bit more bluish around
that bubble type central nebula region. The Ha is a bit more dominant in this image and so everything is
quite red.

Star colours seem fairly accurate so I assume the neb is close as well.
This is also a HaLRGB image so it will be more red than yours for that reason.

http://www.pbase.com/gregbradley/image/101597421

Looking at yours again the background seems a tad blue in the background blue and the reds look a tad too yellow. But its close.

Greg.

[h0ughy]

thanks Greg

[h0ughy]

another tweak? tried to get close to what Greg had - :question: dont think i got there

[strongmanmike]

Looks good but just to throw a spanner in the works :confuse3:...I think it is blue that it now needs :D - just a tad. I find that a red cast in the sky spaces is often mistaken for nebulosity when processing the Eta complex, try just dropping the red background by uping the blue and green a touch....or leave it the hell alone is another option :question: :lol:

Mike

[h0ughy]

I should drop over the fits file to you;)

[gregbradley]

I agree with Mike here. Gotta be careful here because mine had a lot of Ha subexposures added, hence the heavy red nebula. LRGB wouldn't usually look like that and as Mike says a touch more blue, green and pull the red back.

Colour balance is hard eh?

Are you looking at the histograms for all colour channels? It may show the red as being different to the others. You want to try to get them to start at the same spot and that may entail pulling one back or enhancing another.

Another thing to try (god forgive me for suggesting this) is to use "auto colour" in Photoshop. I find it tends to make images too green
(at least PS CS2, I think it improved with later versions). But sometimes it gets it close and a slight tweak and you are there.

Do you have a link to a larger file version of it?

Greg.

[h0ughy]

i dropped over to see Dr Sidonio Physician for the pixellated and he said to take 2 RGB's and have a lie down, this is a very quick and nasty Sidonio but he was showing me some finer points - you could hear the rubber glove snap to the hand when he was showing me. Cough:P with a bit mor massageing and attention to detail, and some re-education i think i might just get there.

i will ftp it and provide the fits and the jpeg - Astroart does not read the 64bit fits as i found out so i will save it as 32bit

[gregbradley]

That version looks more on the money. Nice one.Persistence pays off.

Greg.

[h0ughy]

no knowing a very smart imager helps ;) between mike and yourself

[strongmanmike]

:question:...siiggggghhh..faint..pl onk! :zzz:

[h0ughy]

hey im sorry i experimented - badly:rofl: i think i will go away and practice a lot - as i said Mike, photoshop is not my strong point, think i will remove the post:sadeyes:

[strongmanmike]

It wasn't bad...I just accidentally fainted, sorry......now where was I?..hey where's the image..?...WHERE'S THE IMAGE??.....WHERE'S THE IMAGE???? :mad2: I WANT THE IMAGE :scared:

Deep breath.,..sorry, sorry :sadeyes:

[h0ughy]

ummmm here it is:scared3:

[strongmanmike]

:question:...siiggggghhh..faint..pl onk! :zzz:

:thumbsup:

[Octane]

Would love to have a play around with a FITS/TIFF image if you didn't mind, Dave. :D

H

[strongmanmike]

Noooooooooooooooooooooooooooooooooo ooooooooooooooooooooooooooooooooooo oooooooo :scared::scared:

[h0ughy]

:question: :question: :question: so spit it out - whats wrong, i am a big boy i can take it :sad:

[strongmanmike]

No nuthin :P..just trying to lift your post reply count :thumbsup: :lol:

Ok, seriously I think you nee......:question: :question:...siiggggghhh..faint..pl onk! :zzz:

Sorry...dissregard my imature antics, your latest version was ver....oh oh :sadeyes: :zzz2:

[h0ughy]

mmm i see - i should have delivered a few crowns to you yesterday:P now in the light of day rather than sleep deprived night i think i see what is the problem:face::help2::help3::scared2 : i have just moved to the calibrated screen - my it is aweful. too pink, no blues and as for the other areas....mmmmm:confused2:

[strongmanmike]

Oooooh? :cheers:....... :) :sadeyes: :zzz:

Ok enough silly posts :P

[h0ughy]

ok i tried it agan Mike - and tried not to make the same mistake?:help::question:

[Bassnut]

Geez, whats going on there. Plonk is the word methinks :P.

Latest Sid is a cracker Dave, top work,. :thumbsup:

[gregbradley]

Well done Dave. To me that looks spot on.

Greg.

[h0ughy]

Thanks Fred, it pays not to process with tired eyes, or offend Saint Mike;)!!!



oh i hope it is, and i appreciate the help and suggestions that has been given. the dvd turned up today from mr block so i will have to find time to take it all in:thumbsup:

[gregbradley]

oh i hope it is, and i appreciate the help and suggestions that has been given. the dvd turned up today from mr block so i will have to find time to take it all in:thumbsup:[/QUOTE]

Adam Blocks DVDs are great. It starts from touring around Photoshop and what every tool does. There were some there that are very useful that I had never used before until I saw that DVD.

Greg.

[h0ughy]

LOL i just played the intro - he sounds like DATA from Star Trek

[multiweb]

That repro looks hot! :thumbsup: +1 for adam block's DVDs. I have the whole set. Money well spent.

[gregbradley]

:rofl: Yes that's true. It is a bit sickly sweet but he knows his stuff.

Greg.

[multiweb]

Most of the music in the 'recap' at the end of each chapters is composed and played by his brother I think.

[h0ughy]

is there a set?

[multiweb]

Yeah he's released a few over the years. I have 3 or 4 lying around.

[h0ughy]

repro tweak? at least i got some more star colour