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question about frequency separation method

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  #11  
Old 02-19-2011, 11:24 AM
Caravaggio Caravaggio is offline
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Re: question about frequency separation method

Quote:
Originally Posted by Der_W View Post
Just to make sure I'm getting the problem right: when you're doing a Gaussian blur based separation to fix problem areas in your image, once you work on areas of high contrast, you run into problems?

The first thing I'd try then would be to use something different from Gaussian blur to create the separation.
E.g. the "Filter"-"Noise"-"Median" preserves (especially round) edges pretty well. Or you could try the "Filter"-"Blur"-"Surface Blur". Possibilities are nearly endless :-)!

But if the asymmetric separation works, that's great as well, I just thought this could give you even more flexibility :-).
Yes, Jonas. I was finding that gaussian blur spread the color and luminosity too much on the low frequency layer in areas where there is a strong sudden shift in color and or luminosity. Imagine for example an image of a red apple set against a blue background. A normal, non-asymmetrical split is applied. If you clone on the high frequency layer in the area where the wall meets the apple, the cloning will not look good because both the wall and apple colors are contaminated by each other.

I will try your suggestions to use surface blur or median filter. Thanks.

Last edited by Caravaggio; 02-19-2011 at 11:38 AM. Reason: clarity
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  #12  
Old 07-17-2013, 12:19 AM
JoeFotosiamo JoeFotosiamo is offline
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Re: question about frequency separation method

Quote:
Originally Posted by Caravaggio View Post
Yes, Jonas. I was finding that gaussian blur spread the color and luminosity too much on the low frequency layer in areas where there is a strong sudden shift in color and or luminosity. Imagine for example an image of a red apple set against a blue background. A normal, non-asymmetrical split is applied. If you clone on the high frequency layer in the area where the wall meets the apple, the cloning will not look good because both the wall and apple colors are contaminated by each other.

I will try your suggestions to use surface blur or median filter. Thanks.
I totally agree with the problem with Gaussian Blur in the low frequency layer. I've switched to Dust and Scratches under the Noise filter for a cleaner low freq layer. It takes a lot less time than Surface Blur to render also.

I'll have to test out the difference between dust and scratches vs surface blur vs median filter, though
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  #13  
Old 07-17-2013, 12:21 AM
JoeFotosiamo JoeFotosiamo is offline
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Re: question about frequency separation method

Just love this technique! I do find that having a totally HF layer without color contamination easier to work with.

I don't use Gaussian Blur on the LF layer anymore because of the smearing effect. Dust and Scratches under Noise seems to be better. Will have to experiment with Median filter and Surface Blur, though.



Quote:
Originally Posted by mistermonday View Post
To make a frequency separation in which the color is completely separated from the HF layer as well, do the following:
- Create 3 copies of layer to be separated and name them LowFreq, Color, HighFreq (bottom to top).
- To the bottom copy (LF), desaturate the layer (Image>Adj>Desat or Crtl+Shift+U), and then immediately go Edit > Fade Desaturation and change the Blend Mode from Normal to Hue.
- Next to this same layer apply the Gaussian Blur as you normally would.
- Now select the top layer (HF). Change blend mode to Linear Light. Once again, Desaturate the layer and Edit > Fade Deasaturation and change the Blend Mode to Hue.
- Next do Image > Apply Image using the LF layer as the source as the source just as you do in a normal freq separation.
- Finally, select the middle copy (Color) Layer and change its blend mode to Color and hit Ctrl+E to merge it down onto the LF layer.
Your separation is now complete.
You can experiment by sampling texture with the healing brush and stamoing it on another area. You will heal with texture only. You still need to choose your Radius of separation wisely because you can still make a mess if you are not careful.
Regards, Murray
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