Adding Colour to an Image.

[barkis]

I have just been reading Tony's (Whippy's) post on his adding RGB to his Kelling shot of M33.

He captured the Mono Image of the galaxy using his 110 refractor, and subsequently collected the colour data from a different instrument, namely his 66 scope.

This confused me a bit, but not wishing to contaminate his imaging thread, I thought I would post my confusion in here. How is it possible to do what he, or anybody might do, using two different scopes, with different focal lengths, as this is bound to result in the resultant images being of a different size. What is the explanation, it is probably a simple one, but being a simple git, I don't get it.

Enlighten me please.

Ron.

[SteveL]

Simple answer... resizing the stacked (but unprocessed) images to match before trying to combine them.

[Psychobilly]

and hoping the field is equally "flat" in both sets of data otherwise I suppose you have to correct that as well?

Billy...

[blinky]

Yeah I tried it with my M31 image, failed miserably though :? Anyway if you paste your colour image over the top of your B&W one then select resize from the menu in Photoshop your sorted! Unless your me

[Psychobilly]

When i'm trying to manually align images I start with a new blank image which is significantly bigger than either of the two images i'm looking to combine and then import the images to be combined as seperate layers.

The transform tools are very useful as well allowing you to scale , rotate and distort the two images until you get some sort of alignment between them - especially if you set the mode of one of the layers to difference.

Billy...

[barkis]

Sorry to draw this out a bit, but is it OK to resize an Image using software to fit an image size attained by a telescope of x focal length. Tony made a point about difficulty in orientation of the images that can came from his 66 scope. I think he was referring to matching the orientation of the camera on the scope to take the colour data. If that is the case, why would it not suffice to also orient and resize using software, and therefore not concern oneself with getting it right at the scope. Sorry fellers, I just want to get this imprinted on my brain sufficient to remember it.

Ron.

I was writing this when Billy posted his last one , so perhaps my question has been partly answered there.

[Psychobilly]

I think Tonys "problem" was that he had such a tight crop on his M33 that he didnt have much room for manouvere...

When your LRGB processing its quite common to bin pixels anyway as as the detail in the image comes from the L image.

Drifting slightly off... Since I have started imaging with the Moded 350D and Hutech IDAS P2 I am wondering how much I would gain by converting to a mono setup with filters... the Modded Camera's OSC solutions just seems so convenient...and seems to hover up HA quite nicely.. and handle LP very well

Billy...

[barkis]

Yes, It is amazing how the DSLR has fitted nicely into the astro imagers arsenal, especially with the modifications that assisted it enormously to do that job.

I wonder how much the DSLR has affected the sales of CCD cameras, since the camera price including the mod. is still cheap compared to a high end CCD camera,

Colour or Mono. But where does narrowband imaging fit regarding the DSLR?. It doesn't, does it?

[Psychobilly]

Indded Ron,

That's another question which I was thinking of asking... can you successfully use a modded DSLR for narrowband imaging - I suppose you must be able to get reasonable results as clip in Ha filters etc are available for the DSLR's

I was amazed at the detail I was able to capture in the pacman nebula the other night and didn't have any of the LRGB "hassle" in the processing...

Billy..

[barkis]

I suppose it's a "Watch This Space" jobs Billy.

Anyway, thanks to you, SteveL, and Craig for the gen.

Ron. :salute:

[Whippy]

Ron, I think you may have got the wrong end of the stick slightly. I took both the L and RGB through the 110, and Billy' has it right, as there was no space around the object, I've lost some of the complete image because the RGB image and the mono image doesn't overlap exactly (or even close!), hence it's all a bit wonky.

I think the 66 bit is where I'm contemplating re-doing the whole lot with my ZS66 and Martin (I think) is saying I could just re-take the RGB and resize it to fit over the mono I already have. Downside is that he mentioned doing it on 1x1 binning which would take about 6 hours or so! Or, I could re-do the whole lot with the 66.....

Billy, I have to say that one of the best things L'Missus has bought me this year was my Ha filter. Honestly, if it wasn't for that I would have only had 3 imaging sessions since March when I got my camera. If you have the cash, a camera with a Sony 285 chip (Atik 16HR/314L, SX H9, QHY2 pro and others...) is superb!

Tony..

[Psychobilly]

Thanks to the way this thread "drifted" I suddenly realised the "trick" I had been missing in my image processing... I just had a quick rework of the pacman and will re-visit a load of my images form the last few weeks over what looks like a "wet" weekend for South Wales ...

Billy...

[Psychobilly]

Thanks for the camera advice Tony

Before I built the pier/wedge and obs and started autoguiding as well , there was no way I was going to even consider LRGB imaging now with the ability to take the long subs taht are needed to do it justice then its something i might consider doing ... present economic crisis allowing...

Billy...

[barkis]

Cheers Tony. That's me all over, reading the signs wrong. I really thought you got the RGB from the 66. Sorry mate, I must pay closer attention to what I am reading. :laughing2:

Ron. :oops:

[Helen]

.....but you created a useful thread that meant I learnt something,and caused Billy to have a Eureka moment

Helen

[Whippy]

Cheers Tony. That's me all over, reading the signs wrong. I really thought you got the RGB from the 66. Sorry mate, I must pay closer attention to what I am reading. :laughing2:

Ron. :oops:

You should have heard us lot at Kelling on Saturday night Ron, I don't think there was barely a sentence uttered that wasn't imaging gibberish!

Tony..

[barkis]

Cheers Tony. That's me all over, reading the signs wrong. I really thought you got the RGB from the 66. Sorry mate, I must pay closer attention to what I am reading. :laughing2:

Ron. :oops:

You should have heard us lot at Kelling on Saturday night Ron, I don't think there was barely a sentence uttered that wasn't imaging gibberish!

Tony..

:laughing2: Yeah!, but that's my dilemma mate, I could be in that company, and thinking that gibberish is genuine info, I wouldn't know the flaming difference. :laughing2:

[glennbech]

Off Topic.; Now I started to think about how a Ha filter would work with my moded 10D.... Any ideas?

[MartinB]

The answer to the original question Ron is that you can use software to align and rotate automatically. Using the PS transform tools is torture, a bit like using an abacus to do calculus. I've never used DSS and would have thought this would do it but some people have told me it wont align without doing the combine. That's stupid if it's true.

LRGB imaging is only a faff during the capture stage, having to change the filters. You really have to have a wheel. If you have a motorised filter wheel and decent capture software it is just as easy as OSC but then that is a serious investment and moves beyond the wonderful simplicity of a DSLR.

Processing wise, once you know the routines LRGB is is much simpler than people imagine.

DSLRs are always going to struggle with narrow band. Can be done of course but there are some big problems. The first is that you are only using 1/3 of the pixels when working in Ha, OIII maybe 2/3. Another big provlem is the long exposures required. For a OSC think of 10mins as the minimum. DSLRs will start to kick out a lot of noise by this time. You can overcome some of these problems with long overall exposure and good darks (which must be a pain to get) but it's just the wrong instrument for the job.

[barkis]

Thanks for that Martin. The thing is, I have everything that is required now, Motorised wheel, LRGB, SII, Ha, OIII, LPR,IR. Focal reducers, JMI NGF-S Focuser. But I know too well that there is more to it than having everything you need. I am ready for the winter skies, whether they are ready for me is another thing.

Ron.

[glennbech]

But I know too well that there is more to it than having everything you need

I cannot think of any other hobby or interest that require the same level of knowledge and commitment as Astro Photography. Seriously! That is probably why I'm hooked

[Helen]

I am ready for the winter skies, whether they are ready for me is another thing.

Ron.

Look out Universe - here he comes!!!

[MartinB]

Well you just have to learn from your mistakes Ron. Just try to think when the computer won't talk to the camera, the scope is dewing up, you can't get your target on the chip and you have cables wrapped 5 times round the altitude control knob - ooh what a valuable learning experience!!

[barkis]

Well you just have to learn from your mistakes Ron. Just try to think when the computer won't talk to the camera, the scope is dewing up, you can't get your target on the chip and you have cables wrapped 5 times round the altitude control knob - ooh what a valuable learning experience!!

Just what I needed, more to worry about.

We have had an Inch if rain here this morning. I would say Cumbria must be the wettest County this year. Never mind, I got the foundations for the comfort room finished yesterday.

A totally different day it was. Wall to Wall sunshine.

Ron.

[RobH]

I am ready for the winter skies, whether they are ready for me is another thing.

Ron.

A nice paraphrase of Churchill Ron!!

I've done a fair bit of mixing images from different cameras. Maxim normally handles it pretty well, unless you have a lot of differing field curvature. This can mess things up a bit.

Cheers

Rob