Frequency Separator v1.1


 
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Contributor: Nick Pittas
Frequency Separator for Nuke
Requirements:
10.0, 9.0, 8.0, 7.1, 7.0, 6.3, 6.2, 6.1, 6.0 or later
Linux, Mac, Windows
23 Jun 2016
2905

Now Updated with #Simon Devault's brilliant Merge expression, instead of the PSDMerge operation. Thanks Simon

This is a simple script that uses the Frequency Separation technique from Photoshop, in order to split the image to Texture and Lighting passes so you can control each one separately.


You can use the paint node in either the Low frequency image, to do lighting corrections, or paint the High frequency channel to fix Texture details.

Please remember to always have an Alpha channel in you image, or else the PSD Merge node will not function

Usage:

Freq1

1. Adjust the Gaussian Blur (1) until you dont see the texture detail that you want to correct.

2. Use the RotoPaint2(2) with the Blur Brush to do lighting and chroma corrections without touching the texture

3. You can use any other node after the RotoPaint2(2) and the final Merge(4), to blur sections of the image, like Blurs with mask regions tracked to the object, etc.

4. Use the RotoPaint1(3) with the Clone Brush to correct texture details, like blemishes and spotches.

5. You can also use  tracked surfaces to help with the clone process after the RotoPaint1(3).

 

Examples:

Blur usage for fixing blemishes and lighting

freq2

 

 

 

 

 

 

 

 

k

 

Clone Tool usage for removing texture errors

freq3

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Comments   

 
+1 # jake sparo 2014-07-16 01:51
nice one mate :) didn't even know this technic exist. :D
do you know what the maths is for the psd merge operation ?
 
 
0 # Frank Rueter 2014-08-12 07:49
sounds extremely useful! Could we get some screen shots?
 
 
0 # Gaston Marcotti 2015-07-03 04:36
Thank you very much, i was looking for it since a while!
 
 
+3 # Simon Devault 2016-02-15 22:38
Nice I was looking for that!
It works great, except that it create some bad stuff in the highlights areas. We found out that if you change the color space to sRGB before your tool and switching back to linear after it remove that bug. I'm wondering if there is anyway we can change de psd merge by some regular merges...? That way we can stay linear all the way! And nuke loves Linear!
 
 
+1 # Simon Devault 2016-04-02 13:56
Replacing the PSDmerge by this MergeExpression node solved my problem! (no need to change color space anymore and the bad stuff in highlights are not there anymore!)

MergeExpression {
inputs 2
expr0 "Ar > .5 ? Br + (2*(Ar-.5)) : Br + 2*Ar -1"
expr1 "Ag > .5 ? Bg + (2*(Ag-.5)) : Bg + 2*Ag -1"
expr2 "Ab > .5 ? Bb + (2*(Ab-.5)) : Bb + 2*Ab -1"
name Linear_Light_Me rge
label "Equivalent of a Linear Light\nblending mode in Photoshop"
selected true
xpos 795
ypos 1332
}
 
 
0 # Zebastian Lilja 2016-05-27 13:02
Great work Simon! Thanks for posting this!
 
 
0 # John Fitch 2016-04-02 12:50
Hi,

I cannot get this to work... all I get is a fully blurred image, using the 2 rotos affects nothing...

regarding "Please remember to always have an Alpha channel in you image, or else the PSD Merge node will not function" - where does this required alpha come from ?

on the pics In your example above you're using a jpg image which has no alpha...

any help appreciated !

Thanks.
 
 
+1 # Simon Devault 2016-04-02 13:53
Just put a shuffle node (with full white alpha) right before the psd merge (on both inputs)

I also recommend replacing the PSDmerge by a merge expression like this;

MergeExpression {
inputs 2
expr0 "Ar > .5 ? Br + (2*(Ar-.5)) : Br + 2*Ar -1"
expr1 "Ag > .5 ? Bg + (2*(Ag-.5)) : Bg + 2*Ag -1"
expr2 "Ab > .5 ? Bb + (2*(Ab-.5)) : Bb + 2*Ab -1"
name Linear_Light_Me rge
label "Equivalent of a Linear Light\nblending mode in Photoshop"
selected true
xpos 795
ypos 1332
}

It solves some problems I had with the PSD merge (as mentioned in my previous reply)

Quoting John Fitch:
Hi,

I cannot get this to work... all I get is a fully blurred image, using the 2 rotos affects nothing...

regarding "Please remember to always have an Alpha channel in you image, or else the PSD Merge node will not function" - where does this required alpha come from ?

on the pics In your example above you're using a jpg image which has no alpha...

any help appreciated !

Thanks.
 
 
0 # John Fitch 2016-04-03 03:28
Simon,

thank you, that worked !

Follow up question: any advice on how to pull really good skin tone keys in Nuke avoiding eyes, hair, bg etc ?

I've tried IBK to get a skin tone key, but the results are not as good as in other apps that have dedicated HSL keyer...

Thanks.
 
 
0 # Zebastian Lilja 2016-05-27 13:01
Nice work Nick!
Was thinking I might build something like this myself, did a quick search and found yours.
Works like a charm!
 
 
0 # Adam Chan 2021-04-04 03:38
To simplify even more:

1) in the high pass group, replace the "Merge" and "Expression" nodes with a single "Merge - average"

2) Add a "Grade" to the high pass stream before the final merge, set:
multiply: 2
offset: -1
black clamp: unchecked

3) Replace the final "Expression" with "Merge - plus"

:)
 
 
0 # Marie-Josée Parent 2022-07-31 20:18
i will try it this way. thank you.

Quoting Adam Chan:
To simplify even more:

1) in the high pass group, replace the "Merge" and "Expression" nodes with a single "Merge - average"

2) Add a "Grade" to the high pass stream before the final merge, set:
multiply: 2
offset: -1
black clamp: unchecked

3) Replace the final "Expression" with "Merge - plus"

:)
 

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