Solar Mosaic: normalizing frames

[viktorbravo]

I have constructed a solar mosaic.  I am having trouble getting all the frames at an equal brightness.  The images come out of the Flea3 camera already stretched, so I cant work with the linear image.  Is there any way to equalize the brightness of all the panels before I merge them, or even after they are merged?

http://crashmaster.smugmug.com/Other/Astroimages/i-F5K7sbG/0/X3/Merged-Mosaic-1jpg-X3.jpg

Any guidance on this would be greatly appreciated.

Thanks, Vince

[georg.viehoever]

Try the GradientMergeMosaic process, see http://www.youtube.com/watch?v=H2r3ZYqCaP8 and the forum articles on it (http://pixinsight.com/forum/index.php?topic=3572.0 as a starting point, dont miss the links to the other threads)

Georg

[viktorbravo]

Thanks George, I'll give this a try.  Although after really looking over the image, I doubt its salvageable.  PI will not compile the solar mosaic for some strange reason, so I had to use PS, which can not normalize each frame.  Seeing conditions were wildly variable during the capture process and that's a hard one to reconcile.  Now I guess I know why I dont see many 20 to 50 frame solar mosaics out there. 

[georg.viehoever]

If you make the tiles available to me, I can give it a try.
Georg

[viktorbravo]

I'll try to upload them for you today, thanks George

[viktorbravo]

Here you go George:  http://rattlesnakeobservatory.com/solartiles.zip

[georg.viehoever]

Victor,
actually, I was hoping to get tiles that are already aligned to each other, but not yet merged. If you have these, it would be nice to get them. Otherwise I'll have to do alignment myself, and it's kind of tedious...

Georg

[georg.viehoever]

I did the alignment of the 20 frames manually in Gimp, but had to convert the images from 16 bits depth to 8 bits in the process (Gimp 2.8 apparently only supports 8 bit depth). I then fed them into PI, see screenshot:
- top left: ImageIntegration with average, clipping pixels with value 0. Settings are as shown on the right of the screenshot. Differences are clearly visible.
- bottom left: same, integrating with maximum values. Differences are even more visible than with the first attempt 
- top center: result with GradientMergeMosaic. Default settings as shown on the bottom center, only setting Shrink radius to 10 to get rid of some pixels at the border of each image. Seamless result 

I did not do any further processing. I suppose if you can preserve the 16 bits, you could make a fairly spectacular image showing even the flares at the sun's border. Unfortunately, neither Gimp nor PI (see http://pixinsight.com/forum/index.php?topic=4356.0) has a suitable tool for doing the alignment  while preserving the bit depth.

Georg

[viktorbravo]

That looks great Georg!  I'll give it a shot.  I also could not get PI to align the frames so I used an automatic routine in PS.  Looks like i will have to manually align them, but it works.

Thanks again, Vince