Re: 20030725 NOAA0652 sunspo

From: Eric Ng (ericng_at_cuhk.edu.hk)
Date: 07/26/04 

Date: Mon, 26 Jul 2004 09:13:43 +0800

Hi John,

Are you using LCD monitor to view the images? The contrast and sharpness of
the images usually being enhanced on LCD monitor especially for those model
with low contrast ratio. The dust and scratches filter usually leading to
the image a bit "oil paint" feel, I prefer mild guassian blur filter for
noise remov

To differentiate the noise from granulation, comparing their size difference
should be good way especially when using high imaging focal ratio.

Regards,

Eric

"John Moore" <xxxxx@none.net> 在郵件
news:w9SMc.13864$f4.7658@newsread3.news.atl.earthlink.net 中撰寫...
>
> "Eric Ng" <ericng@cuhk.edu.hk> wrote in message
> news:ce0no1$m6j2@imsp212.netvigator.com...
> > Hi John,
> >
> > Thanks for your comment. I seldom use Maximum Entropy for my webcam
image.
> > Those images were processed with mild wavelet processing in Registax and
> > unsharp masking in photoshop. As the webcam I used is a BW CCD in RAW
> mode,
> > the noise is very minimal.
> >
> > Just curious why you think those "noise" you think was caused by Maximum
> > Entropy? Actually any sharpening filter can enhance the visibility of
the
> > noise. That is very kind of you if you could highlight the noise on my
> > image, I will try using another processing approach and see whether it
can
> > be improved.
>
> Hi Eric,
>
> The noise appears as extra bright, white regions either over the
granulation
> or in the penumbra. To see what I'm talking about, try applying the dust
> and scratches filter in Photoshop. Don't adjust the settings too high as
> otherwise the image will become too smooth, but I think you see a
difference
> between just granulation and granulation mixed with noise. I see the
noise
> in many of the recent images, especially where Max Entropy was applied but
I
> can see now where you didn't use it. The sun is a tough one because it's
> hard to distinguish the noise from the granulation. Don't get me wrong-
> that's a very nice image with less noise than most, but I can see just a
> small amount of it. Probably not worth the effort because the details
more
> than make up for it.
>
> John
>
> > Cheers,
> >
> > Eric Ng
> >
> >
> > "John Moore" <xxxxx@none.net> 在郵件
> > news:A7RMc.13817$f4.8447@newsread3.news.atl.earthlink.net 中撰寫...
> > > These aren't too bad, Eric, although if you're using maximum entropy
for
> > > enhancement, you have to be careful not to intoduce excessive noise
> along
> > > with the granulation. Did you use max ent here? Just wondering,
> because
> > I
> > > see a bit of noise.
> > >
> > > John Moore
> > >
> > > "Eric Ng" <ericng@cuhk.edu.hk> wrote in message
> > > news:ce0lfo$m6f1@imsp212.netvigator.com...
> > > > Dear friends,
> > > >
> > > > Attached was the NOAA0652 sunspot group captured on 25 July, 2004
with
> > 4"
> > > > APO refractor and BW ToUCam Pro at F20 and F40 respectively.
> > > >
> > > > Wish you like it.
> > > >
> > > > http://www.ort.cuhk.edu.hk/ericng/20040725-NOAA0652-closeup.jpg
> > > >
> > > > http://www.ort.cuhk.edu.hk/ericng/20040725-NOAA0652.jpg
> > > >
> > > > Regards,
> > > >
> > > > Eric
> > > >
> > > >
> > >
> > >
> >
> >
>
>

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