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[APML] OT: Re: Webcam Lunar Mosaic --- Reprocessed
Hi Frank,
Thank you very much.
Your article is excellent. The information given is great and very helpful.
Thanks for sharing.
When I get some more time, I probably will reconstruct the whole mosaic
from scratch. Then I'll test some of your procedures, especially the eraser
trick to avoid the seams.
After your advice about contrast and some other suggestions received, I
have managed to reprocess the mosaic image. Here is the result (1.9 MB, but
it's worth the bandwith waste):
http://astrosurf.com/pleiades-ap/20030409/mosaic-L-curves-atw.3000.jpg
This is the result of:
1. Adjusting a bit some transitions between subimages to reduce brightness
differences
2. A careful (and difficult) curves adjustment for better overall contrast
3. Boosting wavelet processing / noise reduction to the limit
I have done 1 in Photoshop, and 2,3 in our PixInsight. The amount of detail
is so high this time, that usual bicubic interpolation resampling does not
convince me to preserve sharpness. I have used a high performance bicubic
spline interpolation algorithm to reduce the image, and quality 12 jpeg
compression to prevent detail losses and artifacts.
I have decided to desist of making a color lunar mosaic for now. I'm not
happy with achieved color consistency --- not an easy work that needs much
more accurate proceedings.
Please look with a blind eye to the multiple seams and mosaicing
artifacts... hope to do better next time.
Best regards,
Juan Conejero.
At 12:45 24/11/2003 -0500, you wrote:
>Hi Juan,
>
>I am enjoying your mosaic very much. The detail along the terminator is
>striking! At your focal length you are resolving some features I don't get
>with my C8. The First Quarter has some very interesting features. I guess I
>have an affinity for high resolution mosaics like this, and I suppose it's
>kind of becoming my specialty :-)
>
>If you're interested, I've just finished an article on the technique I use
>to construct lunar mosaics. I have hopes of getting this published<g>.
>Your mosaic demonstrates a couple of the hardest parts: hiding the seams and
>normalizing the histograms. My article discusses both of these in some
>detail. Since you are using Photoshop to put the mosaic together, the
>article may be of some benefit. I use a CCD camera and calibrate/normalize
>the FITs files before saving as TIFF format, but I'd like to try this with a
>webcam (and film <g>) as I know many lunar imagers use these mediums.
>Anyhoo, the article can be found at:
>http://celestialwonders.com/articles/lunarmosaic
>
>I've never tried a color mosaic and I think you have done a marvelous job
>(and 50 sub images is alot of work)! The only thing I might recommend is a
>curves adjustment to enhance the constrast in the midtones.
>Please don't hesitate to post your next attempt! BTW, I would kill for 8/10
>seeing!
>
>Thanks, Frank
>http://celestialwonders.com
>
>----- Original Message -----
>From: "Juan Conejero" <skycad@ctv.es>
>To: <astro-photo@seds.org>
>Sent: Monday, November 24, 2003 11:00 AM
>Subject: [APML] OT: Webcam Lunar Mosaic
>
> > Hello,
> >
> > It has been a long time since my last posting here; now I come back with a
> > new lunar mosaic. This is definitely off-topic, but I hope you'll like to
> > have a look at it.
> >
> > You can see a reduced version here (1.6 MB):
> >
> > http://www.astrosurf.com/pleiades-ap/20030409/mosaic-rgb-atw.3000.jpg
> >
> > Details:
> >
> > - Philips ToUcam Pro webcam, unfiltered.
> > - Meade LX200 12", prime focus (f/10)
> > - AVI video capture with K3CCDTools 1.0.6
> > - Video frames aligned and stacked in RegiStax 2.1.13.0 beta
> > - Mosaic composed in Photoshop 6
> > - Image restoration and noise reduction by A Trous wavelets processing
>done
> > in Pleiades PixInsight 1.0.0.33 beta
> >
> > Some facts:
> >
> > - Mosaic composed by 50 subimages
> > - 4651 video frames used, about 40% of total frames captured
> > - 4.9 GB of raw data
> >
> > I took the original AVIs on a good and steady night, past april 9, and
>they
> > have been waiting to be processed until now. Seeing was reasonably good
> > (8/10), though not spectacular. I tried to do my best to keep color data
>as
> > accurate as possible. I "calibrated" the camera with a white source before
> > taking the videos, and carefully planned exposure, contrast and gamma
> > settings, which were not changed during the whole acquisition process.
> > Nevertheless, there are slight color differences between some frames which
> > I have been unable to fix/explain, and in general keeping consistent color
> > has been a very difficult task with this mosaic, especially for the
> > brightest areas. Mosaic frame boundaries are also well visible; I know
>they
> > should be corrected, but really don't have the time.
> >
> > I'll appreciate your comments and advice regarding this image, especially
> > about color.
> >
> > If you definitely hate to see a color lunar image, here is the processed
> luminance:
>
> http://www.astrosurf.com/pleiades-ap/20030409/mosaic-L-atw.3000.jpg
>
> Enjoy it.
>
> - Juan Conejero.
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