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Old 19-06-2010, 09:59 AM
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How do you process a mosaic?

I have only done a few mosaics before.

The best one was this one:

http://www.pbase.com/gregbradley/image/98540101

With this one as I recall, I processed each up to being a colour image but no colour processing yet.

I then merged them using Photoshop Photomerge and then once blended I went about the task of evening the backgrounds so the blend lines did not stand out. This took a while.

Once that was done and I had the 4 panel image I did final colour tweakings.

Marc said to normalise the images first. So that would mean getting all the master luminance images of the various panels, and open them in CCDstack or similar and normalising them and saving them. Then repeating that on each RGB master. Then making colour combines out of each panel's LRGB masters. Then blending them in Photoshop or some other program that does a better job of that (Photoshop's merge seems pretty basic no frills).

Is that the best approach?

Does anyone know of a good mosaic stitching program?

I have Panorama factory. I wonder if it also does mosaics?

Greg.
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Old 19-06-2010, 12:14 PM
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h0ughy (David)
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http://pixinsight.com/videos/StarAli...Mosaic/en.html this could help you
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Old 19-06-2010, 12:53 PM
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First I select an area devoid of stars to get the background value in each panel and note that value. Then I do a pixel math in CCD Stack to get the same 'int mode' across all the panels. Then I adjust the display to have the same min value and same DDP across all the panels and make sure nothing is clipped especially in the darks. I then save as scaled 16bits FITS or TIFF files and use registar to register all the panels. I save all the output as FITS. Then off to PS (CS5) where I use a script to load all the registered frames (FITS) in separate layers. I use Trimarchi's Fitsplug to load the fits in PS. I then select them all and use autoblend > panorama ticked (not stacking) and voila! You've got your mosaic ready to start working on. PS works out the blending and levels to match all the gradients. Provided you did all the calibration work properly in CCD Stack.
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Old 19-06-2010, 04:28 PM
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Quote:
Originally Posted by h0ughy View Post
That's great David. Thanks.


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Originally Posted by multiweb View Post
First I select an area devoid of stars to get the background value in each panel and note that value. Then I do a pixel math in CCD Stack to get the same 'int mode' across all the panels. Then I adjust the display to have the same min value and same DDP across all the panels and make sure nothing is clipped especially in the darks. I then save as scaled 16bits FITS or TIFF files and use registar to register all the panels. I save all the output as FITS. Then off to PS (CS5) where I use a script to load all the registered frames (FITS) in separate layers. I use Trimarchi's Fitsplug to load the fits in PS. I then select them all and use autoblend > panorama ticked (not stacking) and voila! You've got your mosaic ready to start working on. PS works out the blending and levels to match all the gradients. Provided you did all the calibration work properly in CCD Stack.
Thanks Marc, I'll try out what you suggest.

Greg.
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Old 19-06-2010, 05:23 PM
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Originally Posted by gregbradley View Post

Does anyone know of a good mosaic stitching program?
One of the IIS AutoPano Pro fan club here. Not cheap but excellent. http://www.kolor.com/
You can test drive it, but it will watermark the output.
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Old 19-06-2010, 05:27 PM
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I'll try out what you suggest.
Make sure you don't normalise the mosaic individual panels because that will stuff up your dynamic range. Pixel maths is used to move the blackpoint to a common value but the rest of the data is not scaled. It's just an overall offset if this makes sense. I'm actually processing 4 panels on Rho right now so when I'm done I'll post a step by step flow of what I did. If it works that is
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Old 20-06-2010, 10:42 AM
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i'll be interested to hear how you go with this greg.

my widefield mosaic was four images in a row, which was hard enough. i was eventually able to make it work ok with Photoshop, but they were all complete RGB panels coming from a DSLR. worked better once i removed some of the stuff shot at lower altitudes (below ~40 degrees) and properly flat fielded. houghy also did an impressive demo of PixInsight with my data.

my CCD/takahashi epsilon mosaic (also Rho region) is not proving to be so successful. it's a two by two mosaic, but i did not have enough overlap between the panels to create a smooth transition. and in trying to get 20 hours of data over three nights at SPSP, i compromised too much and have got too much data at low levels creating too many different gradients.

my first attempt i tried creating separate L,R,G,B mosaics before combining into an L and RGB result. that didn't work very well so next time I will try creating finished L and RGB panels before creating the mosaic for each. but i'm going to need more data over the joins and only managed to get about half of it last weekend as we got a bit more cloud than i was expecting.

good luck.. it's a big project you're tackling! hope you have a *very* nice computer once you start working with all the layers and masks it will need a lot of grunt. even my 4 frame widefield mosaic was a 1GB PSD file with all the layers and by the end making any changes was getting real slow.

cheers
phil
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Old 20-06-2010, 03:47 PM
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I Know after all the complexity discussed above this may seem/be simplistic but i have had good results creating deep sky and lunar mozaics using canon photostich ( comes bundled with other software when you buy a canon camera), joins and blends. Does it in a matter of seconds! Try it.
philip
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Old 22-06-2010, 08:51 PM
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Quote:
Originally Posted by mithrandir View Post
One of the IIS AutoPano Pro fan club here. Not cheap but excellent. http://www.kolor.com/
You can test drive it, but it will watermark the output.
Thanks for the tip

Quote:
Originally Posted by multiweb View Post
Make sure you don't normalise the mosaic individual panels because that will stuff up your dynamic range. Pixel maths is used to move the blackpoint to a common value but the rest of the data is not scaled. It's just an overall offset if this makes sense. I'm actually processing 4 panels on Rho right now so when I'm done I'll post a step by step flow of what I did. If it works that is
Interesting. I am finding with these Baader filters sometimes I need to normalise RGB to get a proper colour combine. Is that an error?

Quote:
Originally Posted by philiphart View Post
i'll be interested to hear how you go with this greg.

my widefield mosaic was four images in a row, which was hard enough. i was eventually able to make it work ok with Photoshop, but they were all complete RGB panels coming from a DSLR. worked better once i removed some of the stuff shot at lower altitudes (below ~40 degrees) and properly flat fielded. houghy also did an impressive demo of PixInsight with my data.

my CCD/takahashi epsilon mosaic (also Rho region) is not proving to be so successful. it's a two by two mosaic, but i did not have enough overlap between the panels to create a smooth transition. and in trying to get 20 hours of data over three nights at SPSP, i compromised too much and have got too much data at low levels creating too many different gradients.

my first attempt i tried creating separate L,R,G,B mosaics before combining into an L and RGB result. that didn't work very well so next time I will try creating finished L and RGB panels before creating the mosaic for each. but i'm going to need more data over the joins and only managed to get about half of it last weekend as we got a bit more cloud than i was expecting.

good luck.. it's a big project you're tackling! hope you have a *very* nice computer once you start working with all the layers and masks it will need a lot of grunt. even my 4 frame widefield mosaic was a 1GB PSD file with all the layers and by the end making any changes was getting real slow.

cheers
phil
I do have an i7 chipped laptop with 8mb RAM. It seems to handle CCDstack quite well for once.

Quote:
Originally Posted by 5ash View Post
I Know after all the complexity discussed above this may seem/be simplistic but i have had good results creating deep sky and lunar mozaics using canon photostich ( comes bundled with other software when you buy a canon camera), joins and blends. Does it in a matter of seconds! Try it.
philip
I think I may have that one. Thanks.

Greg.
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Old 22-06-2010, 08:58 PM
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multiweb (Marc)
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Quote:
Originally Posted by gregbradley View Post
Interesting. I am finding with these Baader filters sometimes I need to normalise RGB to get a proper colour combine. Is that an error?
I don't know if it's an error but my understanding of the normalisation process is to align the lowest point of all subs (usually close to black point) to a common point then scale the distribution of all the data sample equaly in all the frames.

So if you have all your red subs, of course you normalise them prior to do data rejection and stacking but if you have a master red and a master blue let's say and the object has a lot of red in it and hardly any blue, if you normalise the blue to the red you're going to stretch the hell out of it and if you normalise the red to the blue you're going to kill the dynamic range in the red because you're going to compress all the red samples within the 'narrower' range of the blue. Unless I got it all wrong? Maybe some guru can pitch in.
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