Made a mistake

[Gerry Casa Christiana]

Hello

Anyone know how to rectify two different sessions where one time you twisted the Newtonian and now the stacked picture of the two shows two sets of diffraction spikes. I've tried DSS sigma clipping but they are still there. Any ideas anyone? Beyond photoshop I mean

Thanks

Gerry

[RolandKol]

Hi Gerry,

You can try to stack different sessions separately and later blend them into one.
You will end up cropping both images a bit.

If you use Photoshop... it will be quite difficult... I and I am not sure how to do it correctly. Check Files>Scripts>Load Files Into Stack - choose those 2 stacked imaged, Click both options at the bottom (Attempt to Auto Align and Create Smart obj).

Once Smart Obj created, goto Layer>Smart Objects>Stack Mode> choose Median

(you can duplicate object before stacking - and try Mean and Average)

I succeeded only once from 5 different attempts with PS.... it has other options to stack, but I do not recall them anymore unfortunately 

if you do not have LOTS of STARS, you can load separate stacks into layers, make one ~50% visible and rotate/move manually to align the stars (real pain in the ass to be  honest!)

On another hand, 

Pixinsight has a tools named "DynamicAlignment" and "PixelMath" which do the trick all the time... 

P.S.

You can try using Fitswork, - it did a very nice job with my panoramas, but I never tried to stack 2 images with it for streching.

[ollypenrice]

It should be quite easy using Photoshop but, first, make two stacks in preprocessing, one using all the data and one using only the data from one of the nights, whichever is best. One set will then have to be co-registered to the other so they sit on top of each other properly aligned. I would use Registar for this but  you probably have a programme which can do it, maybe DSS?

Next, stretch both stacks (we'll call them Both Nights and One Night) till they look closely similar. Use the colour sampler tool to measure the brightness and colour balance in the same places on both. They need to be close to identical. 

Now copy and paste Both Nights on top of One Night and erase the spikes not present in the bottom layer.

Olly

[Gerry Casa Christiana]

31 minutes ago, ollypenrice said:

It should be quite easy using Photoshop but, first, make two stacks in preprocessing, one using all the data and one using only the data from one of the nights, whichever is best. One set will then have to be co-registered to the other so they sit on top of each other properly aligned. I would use Registar for this but  you probably have a programme which can do it, maybe DSS?

Next, stretch both stacks (we'll call them Both Nights and One Night) till they look closely similar. Use the colour sampler tool to measure the brightness and colour balance in the same places on both. They need to be close to identical. 

Now copy and paste Both Nights on top of One Night and erase the spikes not present in the bottom layer.

Olly

How do I get the layer on top to match exactly to the layer beneath? I mean for moving it. I can't find the option. 

Thanks

Gerry

[ollypenrice]

2 minutes ago, Gerry Casa Christiana said:

How do I get the layer on top to match exactly to the layer beneath? I mean for moving it. I can't find the option. 

Thanks

Gerry

Tricky one. Ideally you need a programme which will do that for you, that is co-register the two images so that the stars have no rotation when placed on top of each other. Once you have done this you can make the top layer only half-opaque and then use the Move tool to slide it so that the top stars are right on top of the bottom ones. You can use the arrow keys for small movements as well.

It is possible to rotate the top image relative to the bottom as well in Ps but I've forgotten, how to do it since I use Registar. Basically you put a top layer star directly over the same star on the bottom layer and then make that the centre of rotation. You then rotate the top layer till all the stars are aligned. I'm sorry I don't recall the details. You might find something online.

Olly

[Davey-T]

As Olly said it can be done in P'Shop which is fine if it's simple rotation otherwise you can try the transform tool but it's extremely fiddly trying to align all the stars much easier using Registar.

Dave

[toxic]

when you stack both runs separately (in deep sky stacker) select the reference frame from the first stack and the use it in the second stack but make it the reference file in the second stack for registering but then un-tick it in the list before stacking and both stacks will line up i hope i explained it ok and hope this helps.

[Gerry Casa Christiana]

9 hours ago, toxic said:

when you stack both runs separately (in deep sky stacker) select the reference frame from the first stack and the use it in the second stack but make it the reference file in the second stack for registering but then un-tick it in the list before stacking and both stacks will line up i hope i explained it ok and hope this helps.

I tried hours yesterday Ollys way but im using Cs2 of photoshop and all my trying just couldn't get it done. 

Ok ill try your way so in DSS have two groups using the group tab at the bottom? and stack them together or separately? using the same reference file? Because I I don't have a problem stacking the two sessions together they line up fine it's just I have 2 sets of diffraction spikes. 

Im a little bit confused by your instructions but I'll try  

[Gerry Casa Christiana]

10 hours ago, toxic said:

when you stack both runs separately (in deep sky stacker) select the reference frame from the first stack and the use it in the second stack but make it the reference file in the second stack for registering but then un-tick it in the list before stacking and both stacks will line up i hope i explained it ok and hope this helps.

Ah I think I got what you mean so the two stacks will sit together perfectly from 2 different frames then I don't have to fiddle in photoshop to stretch the separate stacks to make them fit. So it doesn't sort the diffraction spikes out but for the alignment. It will help! Thanks 

 

[toxic]

yes sorry it is just for the alignment but it will only work for frames that are the same bit depth and size but when this is done you can then layer them as Olly has suggested.

i may have a way of removing 1 set of spikes , could you please post 1 jpeg from each set for me to test this theory please.

[Gerry Casa Christiana]

16 hours ago, toxic said:

yes sorry it is just for the alignment but it will only work for frames that are the same bit depth and size but when this is done you can then layer them as Olly has suggested.

i may have a way of removing 1 set of spikes , could you please post 1 jpeg from each set for me to test this theory please.

Ok sorry been busy how do you want them. 

2 separate sessions or as Olly said one set with 2 nights together and the other set of one night ?

Id be really interested to hear your method. I would buy registar but 179$! I would have paid it if it processed it as well. 

I'll have it on here this afternoon. 

Thanks for trying this 

Gerry

[toxic]

3 hours ago, Gerry Casa Christiana said:

Ok sorry been busy how do you want them. 

2 separate sessions or as Olly said one set with 2 nights together and the other set of one night ?

Id be really interested to hear your method. I would buy registar but 179$! I would have paid it if it processed it as well. 

I'll have it on here this afternoon. 

Thanks for trying this 

Gerry

i would do 2 seperate stacks with 1 file as the reference frame just right click on the file and select reference frame (the same file for both stacks) but in stack 2 untick the reference file so that it wont stack it but will still use it to align the 2nd stack to the first then both stacks will align in photoshop so that you can layer them.

examples below

ps i dont have registar as i cant afford it 

 

 

[Gerry Casa Christiana]

4 minutes ago, toxic said:

i would do 2 seperate stacks with 1 file as the reference frame just right click on the file and select reference frame (the same file for both stacks) but in stack 2 untick the reference file so that it wont stack it but will still use it to align the 2nd stack to the first then both stacks will align in photoshop so that you can layer them.

examples below

ps i dont have registar as i cant afford it 

 

 

Thanks I already did that and it worked fine

and your method for removing diffraction spikes? 

Gerry

[Gerry Casa Christiana]

2 hours ago, Gerry Casa Christiana said:

Thanks I already did that and it worked fine

and your method for removing diffraction spikes? 

Gerry

Well here is what I managed. Any good?

 

Gerry

[Stub Mandrel]

On 04/10/2018 at 11:32, ollypenrice said:

It is possible to rotate the top image relative to the bottom as well in Ps but I've forgotten

It is VERY long-winded!

Set the transparency of top layer to 50%.

Roughly align top right of the image using transform tool, get two images of an obvious star lined up.

Zoom into the centre of the image.

Chose transform tool (triangle)

Edit --> Free transform

You should be able to see the pivot point (small circle with crosshairs).

Move the pivot point to top right by picking it up with the tool moving and scrolling.

Re align the initial star now you are zoomed in and put the pivot point at its centre.

Without deactivating the tool go to bottom left, where everything will look ghastly.

Type in 1 degree into the rotation box on the toolbar, if this rotate the wrong way, try -1.

Refine the rotation, you appear to be able to go in 0.05 degree steps in PS2, until you get the stars aligned.

Choose any other tool and 'accept the transformation'.

You may need to repeat, or to use small movements of the upper layer (CTRL+cursor key for smallest movements) before you are happy.

 

 

 

[ollypenrice]

1 hour ago, Stub Mandrel said:

It is VERY long-winded!

Set the transparency of top layer to 50%.

Roughly align top right of the image using transform tool, get two images of an obvious star lined up.

Zoom into the centre of the image.

Chose transform tool (triangle)

Edit --> Free transform

You should be able to see the pivot point (small circle with crosshairs).

Move the pivot point to top right by picking it up with the tool moving and scrolling.

Re align the initial star now you are zoomed in and put the pivot point at its centre.

Without deactivating the tool go to bottom left, where everything will look ghastly.

Type in 1 degree into the rotation box on the toolbar, if this rotate the wrong way, try -1.

Refine the rotation, you appear to be able to go in 0.05 degree steps in PS2, until you get the stars aligned.

Choose any other tool and 'accept the transformation'.

You may need to repeat, or to use small movements of the upper layer (CTRL+cursor key for smallest movements) before you are happy.

 

 

 

No wonder I'd forgotten! Good post.

Olly

[Stub Mandrel]

11 minutes ago, ollypenrice said:

No wonder I'd forgotten! Good post.

Not as good as @toxic's brief explanation of how to do it in DSS if you still have the source files!

[ollypenrice]

6 hours ago, Gerry Casa Christiana said:

Thanks I already did that and it worked fine

and your method for removing diffraction spikes? 

Gerry

I assume Toxic would do as I would do and just erase the the rotated ones as a layer. Is that what you did? It looks great.

Olly

Edit: I'm now wondering if you could exploit the Ps Blend mode 'difference.' This would pick up the difference between the layers - which would be the rotated spikes. This might make erasing them easier but I haven't tried it.

 

[Gerry Casa Christiana]

16 hours ago, ollypenrice said:

I assume Toxic would do as I would do and just erase the the rotated ones as a layer. Is that what you did? It looks great.

Olly

Edit: I'm now wondering if you could exploit the Ps Blend mode 'difference.' This would pick up the difference between the layers - which would be the rotated spikes. This might make erasing them easier but I haven't tried it.

 

Yes in the end I just erased the extra ones from the combined two nights. It was too much faffing around to try and find a automatic way  Sounds a lot 2 nights but it was only 3 hours of exposures but for such a dim object I’m quite happy. I had to crop it though so the picture is smaller but I can always add more to it I suppose. I lost a little colour in the blue stars but I quite like it as is. 

Gerry

 

[toxic]

ok now for the spikes put both sets of image runs into DSS and select 1 image as the reference file from image run 1 - but this time have all files ticked for both runs as one stack,

now in the lights tab select median Kappa sigma clipping as your stacking method then stack 100 percent of the images (i find manually checking the subs better that the automated way in dss) and that should keep the spikes from run 1 but get rid of spikes from run 2.

i had to find some old files with different orientation to test it as i haven't had to do this for a long time, i didn't have photoshop at the time and i still don't have registar hope this helps

and your image is very nice indeed 

[Gerry Casa Christiana]

17 hours ago, toxic said:

ok now for the spikes put both sets of image runs into DSS and select 1 image as the reference file from image run 1 - but this time have all files ticked for both runs as one stack,

now in the lights tab select median Kappa sigma clipping as your stacking method then stack 100 percent of the images (i find manually checking the subs better that the automated way in dss) and that should keep the spikes from run 1 but get rid of spikes from run 2.

i had to find some old files with different orientation to test it as i haven't had to do this for a long time, i didn't have photoshop at the time and i still don't have registar hope this helps

and your image is very nice indeed 

I'll try that thanks. 

[Gerry Casa Christiana]

On 08/10/2018 at 16:25, toxic said:

ok now for the spikes put both sets of image runs into DSS and select 1 image as the reference file from image run 1 - but this time have all files ticked for both runs as one stack,

now in the lights tab select median Kappa sigma clipping as your stacking method then stack 100 percent of the images (i find manually checking the subs better that the automated way in dss) and that should keep the spikes from run 1 but get rid of spikes from run 2.

i had to find some old files with different orientation to test it as i haven't had to do this for a long time, i didn't have photoshop at the time and i still don't have registar hope this helps

and your image is very nice indeed 

I did try your method to see if it removed the spikes but after stacking both together there was still 2 sets

 

[Stub Mandrel]

5 hours ago, Gerry Casa Christiana said:

I did try your method to see if it removed the spikes but after stacking both together there was still 2 sets

 

For sigma kappa to work you need to have one version in a clear majority over the other.

[toxic]

6 hours ago, Gerry Casa Christiana said:

I did try your method to see if it removed the spikes but after stacking both together there was still 2 sets

 

 

39 minutes ago, Stub Mandrel said:

For sigma kappa to work you need to have one version in a clear majority over the other.

yes you need to set the reference frame with the spikes you want to keep in the first night (and it still works if you only have 10 percent more frames) in the first set than the second but more would be better  so just take 10 percent out of the stack of the second night