Question on sharpening?

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jjocsak
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Question on sharpening?

Unread postby jjocsak » 02.12.2008 19:42

Zooming in on a sharpened image I noticed something that have never seen in any sharpening routine.

Black pixels.

Is this a different type of sharpening, or am I doing something wrong?

If it is normal what was the thinking behind this?

What is the best method of modifying this as it detracts from the quality of the image in some cases?

Or maybe I'm just not doing it right.

The first image below is another program and the second one is Helicon.
Both were taken from the same .DNG file and no retouching was done at all to either one.

You can see the difference very plainly. When this is sharpened the dark pixels turn black and does not look right even at normal resolution

The black pixels only show up when sharpened.

Jeff

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Image

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Dan Kozub
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Unread postby Dan Kozub » 10.12.2008 13:17

Every sharpening routine is based on the aplifying the difference between neighbouring pixels. The main parameters are intenisity (amplification factor) and radius.

Helicon Filter has two sliders - Sharpening for minimal radus and Sharpen Edges for user define radius.

I suspect that you used the first slider in your expriment.

jjocsak
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Unread postby jjocsak » 10.12.2008 14:00

These 2 examples have no sharpening applied at all.

2 different programs were used.

Jeff

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Dan Kozub
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Unread postby Dan Kozub » 10.12.2008 14:26

Now I understand. The black points you see are the result of demosaic algorithm from RAW converter. The first is AHD, the second is VNG. In the Preferences of Helicon Filter you can select RAW converter and demosaic algorithm.

jjocsak
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Unread postby jjocsak » 25.12.2008 21:01

Dan Kozub wrote:Now I understand. The black points you see are the result of demosaic algorithm from RAW converter. The first is AHD, the second is VNG. In the Preferences of Helicon Filter you can select RAW converter and demosaic algorithm.


The problem is I am using Adobe Raw as a converter and do not see an option for that.

Jeff

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Dan Kozub
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Unread postby Dan Kozub » 25.12.2008 22:14

These settings are available only for embedded RAW converter. Try to use it to open your DNG file. If it does not open, upload it to our server (http://heliconsoft.com/ftp.html)

jjocsak
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Unread postby jjocsak » 26.12.2008 01:41

Yes I found it under DCRAW settings and it does make a difference.

I guess I still don't understand.

If I open this image in Adobe Bridge (which uses Adobe Raw) I do not see this happening.

When I open up the same picture in HF (Which uses Adobe Raw) I do see it happening.

What is the difference?

BTW I love this program and have hunted quite a while to find one that works the way I do.

Keep up the excellent work.

Jeff

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Dan Kozub
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Unread postby Dan Kozub » 09.01.2009 16:05

Jeff,

Can you please upload file so I can check it myself? (http://heliconsoft.com/ftp.html)

jjocsak
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Unread postby jjocsak » 10.01.2009 03:53

I uploaded the following.

File:CRW_1747.dng 8137 KB 1/10/2008

I'm not sure why the date is off by a year.

Jeff

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Dan Kozub
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Unread postby Dan Kozub » 13.01.2009 11:15

Thanks, I've got the file. I was able to open it with DCRAW and embedded converter. Adobe DNG opens it too, but with VNG demosaic method which gives above mentioned result. So far I do not see how this can be changed :(


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