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Is UFOCapture 4K coming?
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Lightningwizard



登録日: 2007.10.19
記事: 165

記事日時: Mon Jul 21, 2014 10:52 pm    記事の件名: 引用付きで返信

Yes, because it is a CMOS sensor, at highest gain and some gamma a pattern noise can be observed, especially if the contrast is stretched further. It may disappear when brightness is larger. It also has hot pixels.
The mean image seems calculated in an unusual way, it gives more weight to earlier frames than later frames, look at the star trails, they should be uniformly bright along the trail.



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SonotaCo
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登録日: 2004.08.07
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記事日時: Tue Jul 22, 2014 6:49 am    記事の件名: 引用付きで返信

Lightningwizard wrote:
The mean image seems calculated in an unusual way, it gives more weight to earlier frames than later frames,


This is the most important feature of UFOCapture.
It is the effect of time domain discrete low pass filter (or, simply called "exponential averaging") on each pixel brightness, that enables continuous averaging over frames.
UFOCapture uses this time domain averaging filter and space domain differential filer to detect invisible starts that may cause scintillation.

So it is easy to distinguish the actual star image and hot pixels as below.
It looks most of your masks are that on actual stars.
But anyway they are too many. I will do something for that.



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Lightningwizard



登録日: 2007.10.19
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記事日時: Tue Jul 22, 2014 10:25 am    記事の件名: 引用付きで返信

SonotaCo wrote:
This is the most important feature of UFOCapture.
It is the effect of time domain discrete low pass filter (or, simply called "exponential averaging") on each pixel brightness, that enables continuous averaging over frames.
UFOCapture uses this time domain averaging filter and space domain differential filer to detect invisible starts that may cause scintillation.


That is interesting to know Smile

SonotaCo wrote:
It looks most of your masks are that on actual stars.
But anyway they are too many. I will do something for that.


In my own comparison of the blue mask with the green image in ImageJ, for a case with the mask not covering the actual stars, it really masks exactly the hot pixels and not the stars. If I do an edge detect on the green channel frame, the result is highlighting of the brightest stars and not hot pixels. If I enhance the contrast and then find edges, it shows me more stars and the hot pixels.

When daylight comes I suppose it no longer detects the hot pixels because most of them were not really bright, for example 57 in RGB value, while the light of the stars is added to the background light. Maybe some glow around them is lost in the twilight, making a sharper pixel to be masked.



edges.png
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Green channel is here the edge detect in ImageJ on original green channel stretched contrast 0.01%. Some blue mask pixels overlay green edges, these however are hot pixels, the stars have no blue mask.

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記事日時: Fri Jul 25, 2014 6:36 am    記事の件名: UFOCaptureHD2 V4.10 引用付きで返信

UFOCaptureHD2 V4.10 that contains 4pix scintillation mask mode was released.
http://sonotaco.com/soft/download/UFOHD2_410.zip

V4.10 uses 4 pixel average for the computation of scintillation mask.
4pix mode will reduce the mask for isolated 1 pix mask for hotpixels of CMOS.



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Lightningwizard



登録日: 2007.10.19
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記事日時: Fri Aug 01, 2014 11:06 am    記事の件名: 引用付きで返信

Sorry for the delay!
I am now trying it. It picks nicely the stars this time, all except the brightest stars, for example Vega which in the 25mm F0.95 shows up pretty fat. It then attempts to slow-object mask it. Could it be that these unmasked scintillations still contribute to the Detect Lev values even when slow-object masked? My Auto Detect Lev does not want to return well to the average end of the moving blue bar, probably because of occasional Detect Lev peaks.

Another thing I find is when doing slow shutter speed with this 25mm lens, the mask starts trailing behind the stars, it may require a faster setting (6 is the maximum currently). I found also that the fps setting has an influence here: if the camera operates at 1 fps and the setting is 6 fps the mask trails a lot more. But even when both are the same value I see trailing particularly at SMsize=1.

Is it possible to use a lower minimum for the Head and Tail value? Minimum for Head is currently 10 frames.

I missed a very good meteor previewing when adjusting exposure from 6 to 2 fps, the trail left behind was visible up to 1 second after... Exclamation



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SonotaCo
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記事日時: Sat Aug 02, 2014 8:34 am    記事の件名: 引用付きで返信

The current masking functions of UFOCapture is originally developed for SD video. The target of scintillation mask is point, not circle.
So the hot pixels of CCD is just like the target and the too fat star image on hi-res is not.

On the way of its original thinking, all star image should be covered by scintillation mask with appropriate mask size(sm size), but not slow object mask. The bigger SMsize such as 11 may cover bigger star image. But of course there is limit come from the restriction of real time processing.

Also the slow shutter time, slower than frame rate or too slow frame rateis out of design. UFOCapture watches the event duration by number of frames, but it is not measurable on those inputs.

The 10 frame of the lower limit of Head is needed for the automated analysis of meteor trajectory( to know the background level), so it will not be changed in official versions.

I developed 4pix mode on V4.10 but it seems it is not so good.
It seems some new masking technics should be invented for Point Grey.
Sorry, I went Sony 4K.



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Lightningwizard



登録日: 2007.10.19
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記事日時: Mon Aug 04, 2014 4:48 am    記事の件名: 引用付きで返信

Oh, very nice lightning shots!

4pix mode works better than the classic mode, so I appreciate it. At larger SMsizes also masks around the small stars become large which would not be necessary. The biggest stars may need 9 pixels if computationally possible. Not sure if this would be favorable for the small ones.

I will post some images of last nights in Etc!

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tkuhmone



登録日: 2014.08.26
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記事日時: Wed Sep 24, 2014 11:58 pm    記事の件名: 引用付きで返信

fyi,

There was recently introduced a camera from Samsung, model NX1. Based on DPreview data, this camera could output uncompressed 4K video on HDMI. So there there seems to be more camera vendors supporting 4K output.

introduction:
http://www.dpreview.com/products/samsung/slrs/samsung_nx1/specifications

review article:
http://www.dpreview.com/previews/samsung-nx1
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