Aligning images from different sessions or different scopes, etc

[powerlord]

Several times now, I've combined images from different sessions. Or Ha data with RGB data - but shot with different orientation, etc. Sometimes one image in binned and the other not, so different sizes.

I have failed to get Affinity 'align by stars' to ever work - which seems par for the course as far as I can tell.

So I find myself pulling them into affinity as layers, and having to set the layer to  50% opacity, and faffing around with position and scale until I finally manage to get all the stars to line up. There must be a better way ? Is there a tool which will rotate and scale 2 images or more to align ?

Do people just try to use their stacker for this ? And then somehow export the images once stacker has rotated/aligned ?

stu

[AstroMuni]

1 hour ago, powerlord said:

Do people just try to use their stacker for this ? And then somehow export the images once stacker has rotated/aligned ?

I use Siril for stacking and it seems to be able to cope with rotation/alignment. The stacked image ends up with a few ragged edges but that can be cropped.

Having said that I havent combined images of different sizes together.

Edited July 2, 2021 by AstroMuni

[powerlord]

thanks, but I mean, that will result in a single stacked image.

what I want to do is have an output which is still the 2 images say, but corrected for rotation and scale. So that in seperate layers in affinity I can process them.

I thought perhaps there might be some astro tool that does that sort of thing. e.g.

>rotateAndScale -in image1.tif image2.tif image3.tif -out image1out.tif image2out.tif image3out.tif

kind of thing ?

stu

[AstroMuni]

15 minutes ago, powerlord said:

what I want to do is have an output which is still the 2 images say, but corrected for rotation and scale. So that in seperate layers in affinity I can process them.

If you apply the colour calibration tool in Siril that will rotate the image correctly, but will also apply colour to your stars. Not sure you want that done.

But I think the root of this problem is Affinity's inability to 'align by stars'. So you are manually trying to fix this with a workaround. Is that correct?
So my suggestion would be either use another tool to stack the images and then take into Affinity for further processing or find the fix in Affinity itself.

Edited July 2, 2021 by AstroMuni

[vlaiv]

I use ImageJ and registration plugins - these can just transform (rotate / scale) or even export transformation matrix.

[The Lazy Astronomer]

39 minutes ago, powerlord said:

thanks, but I mean, that will result in a single stacked image.

what I want to do is have an output which is still the 2 images say, but corrected for rotation and scale. So that in seperate layers in affinity I can process them.

I thought perhaps there might be some astro tool that does that sort of thing. e.g.

>rotateAndScale -in image1.tif image2.tif image3.tif -out image1out.tif image2out.tif image3out.tif

kind of thing ?

stu

During stacking, your stacking software should be able to align images to a reference frame without including the reference frame in the stack.

I do LRGB imaging with a mono cam, so do all the time in DSS.

[geordie85]

I use Astro Pixel Processor for combining data sets of different fov/ orientation. It will manipulate one data set, for eg RGB stacks, to exactly match my luminance data set. 

There is also a program called registar that can do the same thing.

[alacant]

Hi

In Siril, simply put your 2 (or any number you like) files in an empty folder, set the working folder to that same folder and hit 'Registration'.

You will end up with two more files in the folder with the prefix ,'r_'.

Those are the aligned-rotated-resized files you mentioned.

HTH

 

Edited July 2, 2021 by alacant

[Paul M]

I've stacked images of the same object but different scopes ( 10in Newt and Mak127) having different image scale and 90 deg rotation using DSS and no effort on my part. Obviously I had to crop the final image due to the Maltese Cross effect. Had I bothered to get the same orientation then there would have been just the border all round caused by one data set having a smaller field than the other. Then I process in PhotoShop

So I see no reason why suitably orientated and similarly sized field data sets from different equipment won't just stack in DSS without any problems.

 

 

[ollypenrice]

I don't know the modern alternatives but I just use Registar for this task. It is infallible.

Olly

[carastro]

I do it all the time.  I stack the separate data individually and then use Registar to stretch/shrink and register the stars and then combine those results in Photoshop using layers.  The top layer needs to be combined at 50%.

I am sure other software must be able to combine the individual registered stacks if you don't use Photoshop.

Carole 

  

[AstroMuni]

On 02/07/2021 at 19:08, alacant said:

Hi

In Siril, simply put your 2 (or any number you like) files in an empty folder, set the working folder to that same folder and hit 'Registration'.

You will end up with two more files in the folder with the prefix ,'r_'.

Those are the aligned-rotated-resized files you mentioned.

I knew it was possible, just didnt know where these files were stored 🙂

[powerlord]

On 02/07/2021 at 19:08, alacant said:

Hi

In Siril, simply put your 2 (or any number you like) files in an empty folder, set the working folder to that same folder and hit 'Registration'.

You will end up with two more files in the folder with the prefix ,'r_'.

Those are the aligned-rotated-resized files you mentioned.

HTH

 

wow. Just tried this in Sirl (on a mac so would prefer mac solution). worked a treat with 2 of the 3 I tried- maybe need to crop the other one as it was stacked all over the place.

It's a crying shame it's from the same UI/UX school of mess Pi is from - otherwise I think a lot more people would use Sirl.

As it is, even with instructions above, I found I needed to 'convert' the files first so that they would be named into a sequence before Sirl would recognise them as a sequence to register.

but give it it's due - it did work! thanks for the tip.

stu