Combining RGB data

[nmoushon]

Some of you have seen my first light post with my SBIG 2000XM. In it I explained my horrible start to the night but managed, in the end, to get some usable data. I also explained that for some reason my RGB data was messed up. Well I was able to salvage it, though it might need to be redone anyways. I'm haveing trouble getting color to come out once I have combined all the data together. So wondering if someone can point out what I'm doing wrong. Here's what I'm doing:

1-Load up R - G - B seperately in PS (I'm using DSS to stack and PS to do all other work btw)

2-Stretch each a bit to bring out data. Not a full stretch though just a bit.

3-Open a New file and select "RGB Mode" and change DPI to 300

4-Select All of R and copy it over to the New File and paste it into the R Channel

5-Repeat set 4 for G and B

6-I then start stretching the image. This is where I'm stuck as no color is coming out no matter how much or how hard I stretch the data.

I read a couple blogs where you need to go the the Channels menu and selet merge channels but for some reason its greyed out. So I think this might be the cause but not sure.

Also I've noticed the my B data is not aligned with my R&G data. Some reason the object has moved about half a stars width. Not sure how but it happened. Is there a way to align the B data with the B&G data? The only way I know how to align is with DSS and thats not an option here with RGB data....correct?

[ollypenrice]

Honestly, I'd advise you to buy AstroArt 5.0. The price is reasonable (more than reasonable really) and the aligning and colour combining can be done so easily. Likewise calibrating and stacking.

Olly

[Zakalwe]

Or Registar. It's a one trick pony, but its brilliant at that one trick!

Make sure that you changes the RGB stacked subs to Greyscale in PS. Otherwise the Merge Channels will not be available.

[MartinB]

Using the merge command in channels is the easiest way to combine the RGB using PS.  The seperate RGB images need to be the same size and greyscale.  Also carefully aligned because there is nothing you can do to realign the channels once merged.  Nothing wrong with photoshop for merging RGBs.

[ollypenrice]

Using the merge command in channels is the easiest way to combine the RGB using PS.  The seperate RGB images need to be the same size and greyscale.  Also carefully aligned because there is nothing you can do to realign the channels once merged.  Nothing wrong with photoshop for merging RGBs.

Yes, I must try it. For historical reasons I've never done so. What about weighting?

Olly

[MartinB]

Yes, I must try it. For historical reasons I've never done so. What about weighting?

Olly

In Maxim, presumably like in AstroArt you can adjust the weighting and, when I'm feeling conscientious I use this data to choose the sub exposure times for the different filters.  Maxim will also auto equalise background levels.  You effectively do the same thing manually in PS by correcting colour background bias with levels and then tweaking the different channels to suit.  There's nothing scientific about my images!

[Ewan]

Some of you have seen my first light post with my SBIG 2000XM. In it I explained my horrible start to the night but managed, in the end, to get some usable data. I also explained that for some reason my RGB data was messed up. Well I was able to salvage it, though it might need to be redone anyways. I'm haveing trouble getting color to come out once I have combined all the data together. So wondering if someone can point out what I'm doing wrong. Here's what I'm doing:

1-Load up R - G - B seperately in PS (I'm using DSS to stack and PS to do all other work btw)

2-Stretch each a bit to bring out data. Not a full stretch though just a bit.

3-Open a New file and select "RGB Mode" and change DPI to 300

4-Select All of R and copy it over to the New File and paste it into the R Channel

5-Repeat set 4 for G and B

6-I then start stretching the image. This is where I'm stuck as no color is coming out no matter how much or how hard I stretch the data.

I read a couple blogs where you need to go the the Channels menu and selet merge channels but for some reason its greyed out. So I think this might be the cause but not sure.

Also I've noticed the my B data is not aligned with my R&G data. Some reason the object has moved about half a stars width. Not sure how but it happened. Is there a way to align the B data with the B&G data? The only way I know how to align is with DSS and thats not an option here with RGB data....correct?

Hi Nmoushon,

I cant help you with the lack of colours but all your steps do work with my NB subs.

The misaligning can be overcome in PS as well, it's a bit of work but it will work for you, i did a meridian flip last night (the first i might add), got lost as to the position of The Bubble, anyway my Ha stack was -124.31 degrees off from the O3/S2, all i do is this :-

1) Load the Ha & O3 OR S2 & do a light stretch to help with seeing the stars clearly.

2) Use the Move tool & drag Ha onto lets say for arguments sake O3, keep your finger on the mouse & when it flashes drag the pointer back to the main screen then let go.

3) Now change Opacity to 50%, you should now be able to see how much your subs are misaligned.

4) Goto SELECT - ALL (to select the whole Ha frame), using the MOVE tool you can drag the Ha to roughly where it should be positioned on top of the O3 layer.

5) If need be you can also goto EDIT - TRANSFORM to Rotate as well (as i did), if you do rotate do it a little at a time, align the centre as near as, then align the stars further outwards, if you look at the top the amount of degrees of change made will be shown in a box, when aligned make a note of the number.

6) You can also goto IMAGE - IMAGE ROTATION to flip the image Horizontal or vertical if needed.

7) Now close & quit if you wish, open all your files, do your light stretches then click the offending image, SELECT - ALL - EDIT - TRANSFORM - ROTATE now enter the number you wrote down (you did write it down eh !!!) & the sub should align exactly where it should go.

I am no expert Nmoushon but with all the mistakes i have & will make i am learning all these little bits so i hope it helps you out in some way, be aware you will end up with a slightly shaped final image doing this but at least all is not lost ie as below.

[Freddie]

That's a very complicated way to align the subs. Why not just align them to the same reference frame when you stack them in DSS?

[nmoushon]

Ewan - Thanks for the detailed explaination. I'll try again tonight since is will be a cloudy evening.

Freddie - Could you explain a little more? I though you couldnt stack RGB data together in DSS. Or am I missinderstanding what your saying?

[Ewan]

 sorry Freddie, do you mean i can load my Ha stack of subs in DSS along with one sub of O3 & use the O3 as a reference frame to align the Ha ?

EDIT:-

I just loaded 12 Ha into DSS & 1 O3 image, used O3 as reference frame, it indeed stacked only 12 frames of Ha but in PS when overlaid on top of a stacked O3 they still didn't align up ?

[Freddie]

Yes, you use the same frame in each stack as a reference but don't include it in all the stacks.

RGB as an example, but works with any combo of files. Load the Rs, right click on one of them and check "use as reference" at the top of the options. Check ALL the frames and stack them all. Now load up your Gs AND the single R frame you used as a reference. Right click on the R frame and again select "use as reference". Now check all the frames EXCEPT the R and stack as usual (you obviously don't want a R frame in your G stack!!) Repeat for the Bs again using the single R frame as the reference but not included in the stack. All three of your DSS stacks are now perfectly aligned and can be combined in PS using channels very easily. 

[Ewan]

Sorry Nmoushon my way is incredibly longer how stupid do i feel, i didn't know DSS could do that.

Yes, you use the same frame in each stack as a reference but don't include it in all the stacks.

RGB as an example, but works with any combo of files. Load the Rs, right click on one of them and check "use as reference" at the top of the options. Check ALL the frames and stack them all. Now load up your Gs AND the single R frame you used as a reference. Right click on the R frame and again select "use as reference". Now check all the frames EXCEPT the R and stack as usual (you obviously don't want a R frame in your G stack!!) Repeat for the Bs again using the single R frame as the reference but not included in the stack. All three of your DSS stacks are now perfectly aligned and can be combined in PS using channels very easily. 

Thanks for that Freddie that should save me some time, so i take it leave your misaligned stack until last then.

[nmoushon]

Yes, you use the same frame in each stack as a reference but don't include it in all the stacks.

RGB as an example, but works with any combo of files. Load the Rs, right click on one of them and check "use as reference" at the top of the options. Check ALL the frames and stack them all. Now load up your Gs AND the single R frame you used as a reference. Right click on the R frame and again select "use as reference". Now check all the frames EXCEPT the R and stack as usual (you obviously don't want a R frame in your G stack!!) Repeat for the Bs again using the single R frame as the reference but not included in the stack. All three of your DSS stacks are now perfectly aligned and can be combined in PS using channels very easily. 

Holy cow! Had no idea DSS could do that! I'm super excited now lol. Now only the get my wife of my laptop. 

Sorry Nmoushon my way is incredibly longer how stupid do i feel, i didn't know DSS could do that.

 

No worries. I was prepaired to do it in PS as I thought that was the only way outside an expensive program. Glad to know it can be done in PS to though.