Merging Images to create Solar Full Disk

[Purplehayze104]

Hi All

Just wondering if anyone knows of a good photo merging software that I can use to create mosaic of my full disk solar images ??

i've use PS5 but seem to have a bit of trouble, some of the images are merging and then some are ramdomly placed elsewhere on mosaic & don't line up, gets a little frustrating, any help on this matter much appreciated. 

regards & clear skies

john

[michael.h.f.wilkinson]

I use the free program AutoStitch for win64

http://www.cs.bath.ac.uk/brown/autostitch/autostitch.html

Works well for me, and is essentially fully automatic

[Purplehayze104]

thanks Michael

i'd not come across that one, is there any particular file type autostitch prefers to use for processing ?? (at work at moment & cant check it out) mine are stacked into .tiff's at the moment.

great image by the way, hopefully will get mine sorted soon once ive tried this bit of software.

kind regards

john

[JB80]

MS ICE handles tiffs and that is what I use if I can't get Photoshop to work. If I'm honest I also have autostitch because some days none of them want to do the job.

[michael.h.f.wilkinson]

AutoStitch reads most image files (including my stacked TIFFs). The key drawback is that the output is only in JPEG with at most 99% quality setting. I have treid MS-ICE, but that often borks on mosaics in H-alpha (though sometimes it does come to the rescue when AutoStitch fails (rare, mysterious cases)

[Purplehayze104]

thanks for the info Michael & JB80 much appreciated will give both a try.

kind regards

john

[ollypenrice]

I tried ICE but it never made a coninuous circular limb for me. In the end I just used Layers in Photoshop and edged each component into shape by hand. This had the advantage that I could tweak the brightness of each component to get a seamless joint.

Once constructed I would give the whole image a more natural look by very slightly brightening from the centre outwards using the circular marquee and curves. I'd gradually increase the size of the marquee (well feathered) so the middle ended up a tad brighter than the rest. This could be called cheating   but the trouble is that you can't rely on the brightness distribution of the components anyway. They are bound to have gradients.

I don't rely on software for my deep sky mosaics either. I find it takes you so far but not all the way, so final assembly is still by hand in Ps Layers.

I'm not at all a serious solar imager, be it said.

Olly

[michael.h.f.wilkinson]

Gradients can be a problem, as my first full disk animations show. There is an automatic trick to get rid of them, however. What I am doing now is to add all the aligned images together, so I get an average image. I then perform either a median filter or a morphological middle filter to get rid of any fine detail. You then end up with a very decent "average" solar disk. I then subtract this from all images, and remove all fine detail from the different image with a morphological middle or median filter with large radius (200 pixels in my case). Subtracting this from the original image remove the gradient. I am writing some code to automate this fully.

[michael.h.f.wilkinson]

I have just been pondering the above method over lunch, and I think it actually has a slight flaw. The above method assumes the problem is an additive one, which it isn't. Areas that are too dark do get boosted in average brightness, but the amplitude of the grey-level variations stay the same, resulting in visually duller contrast. Gradients in these images are due to changes in system sensitivity, improperly corrected by the flats. This is a multiplicative problem. The best way to solve this is by multiplying each image pixel-wise by the pixel-wise ratio of the smoothed average disk and the smoothed image. To avoid division by zero errors and instability in background areas, you should add an offset to both numerator and denominator.

[Davey-T]

Photoshop does a so so job of assembling a mosaic but usually fails to fit a few bits which I mess about fitting manually, bit tedious as you have to keep moving layers around and to the front or back and using the eraser to blend them.

Something automated would be a boon Michael, I'm having trouble loosing the joins in my mozaics, I've tried the noise median filter which removes light bands on the joins but not dark ones.

Not a P'Shop expert so mostly trial and error on my part.

When I looked at the Autostich site I thought it said it only supported JPEGs ?

Dave 

[michael.h.f.wilkinson]

Photoshop does a so so job of assembling a mosaic but usually fails to fit a few bits which I mess about fitting manually, bit tedious as you have to keep moving layers around and to the front or back and using the eraser to blend them.

Something automated would be a boon Michael, I'm having trouble loosing the joins in my mozaics, I've tried the noise median filter which removes light bands on the joins but not dark ones.

Not a P'Shop expert so mostly trial and error on my part.

When I looked at the Autostich site I thought it said it only supported JPEGs ?

Dave 

For output, yes, for input, it accepts almost anything. Setting output jpeg quality to 99% gets pretty good results , but 100% is not supported

[Zakalwe]

Photomerge in Photoshop for me. Make sure to crop the edges of the panes first if it is struggling to merge them.

[Davey-T]

For output, yes, for input, it accepts almost anything. Setting output jpeg quality to 99% gets pretty good results , but 100% is not supported

Thanks Michael, just tried it on my last mosaic and it fitted all the bits together, four more than PS  managed 

Just need to get rid of the dark bands now.

Dave

[Davey-T]

Photomerge in Photoshop for me. Make sure to crop the edges of the panes first if it is struggling to merge them.

Been there done that, spent hours fiddling with layers, managed to get it to do all but 4 layers yesterday, just put it through Autostitch and it did all panes first go, the only slight down side appears to be output only in JPEG.

Dave

[michael.h.f.wilkinson]

Note that I use A LOT of overlap between panes. If your flats are decent, you get pretty smooth results if you use gain compensation ON in AutoStitch. I also find multi-band blending with 2 or 3 bands works best

[Purplehayze104]

wow dint realise how much goes into these images processing wise, been following a couple of videos from Ken Crawford & another from youtube similar but different ways of processing which do tend to work but I don't seem to get as much detail on mine, prolly coz they from a larger scope etc etc but have been happy with my results from my lil lunt35. thankfully this thread has help a lot with finding stitching software that works well for me. im in the process of redoing my image at the moment from other week so fingers crossed will be better results than last effort, having to merge all my prom images by eye in PS5 as cant get them to do what I want in any stitching software just don't like em.

regards

john

[Zakalwe]

Been there done that, spent hours fiddling with layers, managed to get it to do all but 4 layers yesterday, just put it through Autostitch and it did all panes first go, the only slight down side appears to be output only in JPEG.

Dave

Yeah...thats one of the reasons why I don't use it. I tend to stitch the image before sharpening. A JPEG output makes it that much harder to drag the prominence detail from the dark stuff.

Having said that, Michael produces superb images, so his workflow and skills are clearly superior to the one that I use