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pitero
Joined: 07 Feb 2010
Posts: 9
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 Posted: 8th Feb 2010, Mon, 20:31 Post subject: [RT-3.0A1 WIN7 32bit] terribly noisy photos |
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[RT-3.0A1 WIN7 32bit] terribly noisy photos
I've noticed that photos from my k10d are too noisy that I would expect. I took so a dark frame photo (with lens cap on) with parameters iso 1600 and time about 1/4 s and... that file opened in RT looks like a set of colorful points. It's impossible to have so many hot pixels (sorry I don't know how to attach a file as an example). The same file opened in other software looks quite normally. I'm wondering why.
I repeated the experiment for the old nikon d70 and the same story.
I don't know what caused that. Is that maybe any bug in determining black level automatically? When I set it to value approx. 11000-11500 (for pentax k10d) the photo starts to look as in other applications.
Any suggestions? (I was not sure if to put that here as a bug or in another forum...) |
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pitero
Joined: 07 Feb 2010
Posts: 9
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| Posted: 8th Feb 2010, Mon, 20:37 Post subject: Re: [RT-3.0A1 WIN7 32bit] terribly noisy photos |
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| Upps, I haven't noticed that earlier - RT introduces automatically exposure compensation about +3ev for those files. But why? When I set it to 0 ev it's almost ok although a bit of noise is still visible (I mean noise of white and gray pixels now, quite a lot of, not hot pixels) |
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DrSlony
Joined: 02 Dec 2007
Posts: 934
Location: London, Rainy Kingdom
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| Posted: 9th Feb 2010, Tue, 20:06 Post subject: |
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Hey, your questions are easily explained:
1- Read the manual http://www.rawtherapee.com/?mitem=6
2- Turn off exposure > autolevels (see point 1)
3- The preview in RT when not set to 100% uses some kind of algorithm that produces a rough sharp image where pixels are not interpolated nicely and noise is preserved if not amplified. Perhaps it uses pixel binning (but that would get rid of the noise), or just discards most of them, I don't know. Either way if you zoom in to 100%, or render the image, it will be much smoother.
Also, see:
http://rawtherapee.com/forum/viewtopic.php?t=1428 |
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pitero
Joined: 07 Feb 2010
Posts: 9
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| Posted: 9th Feb 2010, Tue, 20:23 Post subject: |
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| DrSlony wrote: |
3- The preview in RT when not set to 100% uses some kind of algorithm that produces a rough sharp image where pixels are not interpolated nicely and noise is preserved if not amplified. Perhaps it uses pixel binning (but that would get rid of the noise), or just discards most of them, I don't know. Either way if you zoom in to 100%, or render the image, it will be much smoother. |
Sorry my fault for not reading manual.  However even when auto levels is off and size set to 100% image is a bit noisy. Not too much but more than in other software. Setting black level helps then. Why it's like that? |
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DrSlony
Joined: 02 Dec 2007
Posts: 934
Location: London, Rainy Kingdom
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| Posted: 9th Feb 2010, Tue, 20:32 Post subject: |
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| I can't help you if you don't upload the RAW and a JPG (low compression, high quality!) or better PNG demonstrating problem. See that last link, it will tell you where to upload the RAW and PNG/JPG. |
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pitero
Joined: 07 Feb 2010
Posts: 9
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| Posted: 9th Feb 2010, Tue, 20:50 Post subject: |
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| DrSlony wrote: | | I can't help you if you don't upload the RAW and a JPG (low compression, high quality!) or better PNG demonstrating problem. See that last link, it will tell you where to upload the RAW and PNG/JPG. |
Here you have the photo (zoom was set to 100%):
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paul.matthijsse
Joined: 07 Oct 2008
Posts: 667
Location: Dieulefit, France
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| Posted: 9th Feb 2010, Tue, 21:40 Post subject: |
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| This is what you may expect at 1600 iso on dark/black areas. Try to shoot at 100 or 200 iso and your problem is away. |
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pitero
Joined: 07 Feb 2010
Posts: 9
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| Posted: 10th Feb 2010, Wed, 09:27 Post subject: |
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| paul.matthijsse wrote: | | This is what you may expect at 1600 iso on dark/black areas. Try to shoot at 100 or 200 iso and your problem is away. |
not sure, those small white pixels are not visible in other software (with exception of few bad pixels I have and pity that it's not possible to remove them with RT ) |
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