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Reduce "Scanner Streaks"

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  #1  
Old 05-25-2003, 11:41 AM
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Flora Flora is offline
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Reduce "Scanner Streaks"

You might have already used it, but I discovered it while trying to find a way for reducing 'Scanner Streaks' ...

I'm talking about the De-Interlace Filter.

I tried it on several pictures and the results I got, even though far from perfect, were very encouraging...

For the following example, I used the picture submitted for Restoration Challenge #38 :

1) Duplicate the Background Layer.

2) Since the De-Interlace Filter seems to be working on horizontal lines only, if the streaks in your picture are vertical, Rotate the image by 90° (either way: CW or CCW)

3) Filter->Video->De-Interlace:

Eliminate -> Odd Fields
Create New Fields by-> Interpolation

4) Rotate your image back ...

5) Change the Layer's Blending to Lighten, press "V" (Move Tool) and use the Arrow Keys to nudge your Layer until the lines have nearly disappeared.

6) Add a Layer Mask ->Hide All and using the Eraser Tool, selectively uncover the corrections.

P.S. In the example, I only worked on reducing the streaks and beside a Curves Adjustment and a light Sharpening ... No other correction has been done ...
Attached Images
File Type: jpg de-interlacebennie.jpg (99.2 KB, 131 views)

Last edited by Flora; 05-25-2003 at 11:49 AM.
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Old 05-25-2003, 12:16 PM
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jeaniesa jeaniesa is offline
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Flora,

This seems like a really neat tip, but when I try the de-interlace filter, I don't see that it actually does anything. What am I missing? I can still change the layer blending mode to lighten and move it and see results - but I don't see any difference before/after running the de-interlace filter. Should I?

Thanks,
Jeanie
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Old 05-25-2003, 12:36 PM
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Jeanie,

the difference I saw trying both methods, with and without De-Interlace, was in the smoothness .... but, if you don't see any, it might be my monitor or my eyes....
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Old 05-25-2003, 01:04 PM
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After playing around with it a little more, I discovered that if I reduced the size of the picture (so that the streaks were smaller), I did notice the de-interlace filter smoothing things out a bit. But, on larger pictures, it doesn't seem to make that much of a difference. A very slight motion blue in a direction perpendicular to the streaks seems to have a similar effect though - and can be adjusted based on the size of the image.

Thanks again Flora!

Jeanie
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Old 05-25-2003, 01:21 PM
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...In fact I've tried it only on small size pictures ..... I'll just have to 'experiment' with larger sizes .....

One question ....
Quote:
..A very slight motion blue in a direction perpendicular to the streaks seems to have a similar effect though - and can be adjusted based on the size of the image...
... you really got me here ... ...What is it... and how do you do it?

Thanks ....
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Old 05-25-2003, 04:15 PM
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CJ Swartz CJ Swartz is offline
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Flora -- I'm betting that the "motion blue" Jeanie mentioned will turn out to be "motion blur" (just one little letter ) - like what you did on the Moire Challenge a few months ago.

Flora, thanks for always looking for new strategies -- I thnk I used the de-interlace filter once to make TV lines, but I'm not sure. I didn't notice any difference myself when trying your method vs just moving the layers, but my vision is not very good.
I decided to see some of what it would do on lines, and made an image to show the effects of the different settings. I'm not sure what to make of the results, but there is definitely a difference.
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File Type: jpg de-interlacing.jpg (38.0 KB, 35 views)
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Old 05-25-2003, 04:40 PM
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Quote:
Originally posted by CJ Swartz
Flora -- I'm betting that the "motion blue" Jeanie mentioned will turn out to be "motion blur" (just one little letter ) - like what you did on the Moire Challenge a few months ago.
Thank you for catching my typo CJ! I was about to go into a long description about motion blur - didn't even realize I had a typo and that was the cause of the confusion!

Interesting test results CJ. Now if we can only figure out what it means!

Jeanie
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Old 05-25-2003, 04:57 PM
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Hi CJ, Jeanie,

Thank you very much for your reply
Quote:
..I'm betting that the "motion blue" Jeanie mentioned will turn out to be "motion blur" ....
...how silly of me not to realize it .... ... It's not only my eyes .... it's my brain too ...

CJ,

thank you so much for having taken the time to dig deeper into the De-Interlace Filter ..... After having tried it on a bigger sized picture, I couldn't see the difference either .... so back to 'experimenting' ....

..So...if possible for me, I'll just delete this useless 'tip' as not to waste any precious space at RP ....

Thanks again to both of you...
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Old 05-26-2003, 02:53 AM
Stephen M Stephen M is offline
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A video de-interlace filter probably will not work well on images which are not characteristic of a video source in the spacing of the missing rows. When working with video caps, if one can capture two successive frames and then blend them in darken or lighten mode, there is no need to interpolate or dupe as with de-interlacing filters. <g>

I agree, motion blur can be of help as an alternative - but sometimes gaussblur does better even if it blurs in both directions, but it all depends on the image. Darken blend would be good to try, or lighten - depending on the missing lines luminance value.


Stephen Marsh.

Last edited by Stephen M; 05-26-2003 at 03:03 AM.
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Old 05-26-2003, 03:31 AM
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Hi Stephen,

Thank you very much for your help...

I've read only very little on the De-Interlace Filter and you are absolutely right ....

Mine was just an experiment after having worked on Sanda's picture .... which was very small in size and which I strongly magnified as to see even the smallest changes in details .... Compared to the plain Lighten and nudge, it seemed smoother ... so ... in the heat of the moment ... I thought to share this .... but, later, trying it on a bigger sized picture, I couldn't see any difference either ....

I tried the 'Motion Blur' on another picture but, as often happens, the results vary from picture to picture, so, I wasn't very satisfied with that solution for that particular picture .... so, as you pointed out, good old 'Gaussian Blur' will be my Tool of choice for that kind of problem ....

Thanks again ....

I've already tried to delete this thread, but I'll have to bother someone of higher rank, since I'm not allowed to ...
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