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High-Pass & Gaussian – Choosing the radius

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  #1  
Old 11-15-2004, 06:44 PM
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Post High-Pass & Gaussian – Choosing the radius

If you take a look at the threads concerning sharpening / blurring / high-pass filter you will quickly discover two things:
1) The radius is very important;
2) Nobody tells you just how to get it right.

Hope this will help out.
[details]

They say the best way to learn is to teach - had to rewrite this three times because I kept on finding better ways to do it.

Have fun,

byRo
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File Type: zip byRo Graphics Eq.zip (1.7 KB, 1839 views)

Last edited by byRo; 11-15-2004 at 06:55 PM. Reason: Action attached
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Old 11-15-2004, 09:39 PM
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Ed_L Ed_L is offline
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Please don't add another tutorial for a few days. Although I'm sure this is explained very well, it's going to take a couple of days to sink in. When it does, I'll be looking for another one from you. These are great! Thank you for putting in the work so we can all understand it better.

Ed
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Old 11-15-2004, 11:09 PM
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DannyRaphael DannyRaphael is offline
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Ditto, "Thank you for putting in the work so we can all understand it better."

An awesome package of knowledge.
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Old 11-16-2004, 06:20 AM
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Graphics Eq. - How to use

As Danny pointed out to me - the "How to use the Graphics Eq." part could use some (a lot) more detail.
Tonight I'll edit the tutorial, but in the meanwhile.....

The green band-pass layers are all initially turned off with blending set to "Normal".
Starting from the bottom:
- turn the layer on;
- take a look at the information and decide:
1) This is something that will help;
2) This is something that is working against you;
3) Neither one or the other.
In the first case change the blending from Normal to Overlay. If the effect is too much change to Soft Light, or if you want more change to Hard or Linear Light.
In the second case invert the layer <ctrl><I> and proceed as above.
In the third case just turn it off and go to the next above.

Note: the initial "Normal" blending is only to help visualize the content of each band, if you are going to use it change the mode to Overlay etc..
If anything else isn't clear - PLEASE ASK.

byRo
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Old 11-29-2004, 11:19 PM
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SWEngineer SWEngineer is offline
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Rô, excellent work here! Sadly (for me), I only have Elements, so I can't play with your action file. (If you can coax Richard Lynch into helping make this compatible with his HPA3 work, I'd be deeply indebted to you both.)

Am I correctly understanding that these are true band pass filters? e.g. the 10 - 20 layer (filter) would be (using the invert / linear light subtraction trick) Highpass(20) - Highpass(10) or equivalently GaussBlur(10) - GaussBlur(20)?

This opens up an entire new dimension for selectively modifying images. In addition to tone & color, its obvious now that one can work with "frequency" with near equal ease. The example you posted and your suggestions for using your graphic equalizer barely scratch the surface of what can be done with this tool / idea. At least from my perspective as an artistically challenged, but mathematically inclined person, this may be the most valuable tutorial I've ever read. Thanks so much for sharing this. You are awesome Rô.

-Mark
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Old 11-30-2004, 05:10 AM
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Hi there, Mark,

Quote:
Originally Posted by SWEngineer
Am I correctly understanding that these are true band pass filters? e.g. the 10 - 20 layer (filter) would be (using the invert / linear light subtraction trick) Highpass(20) - Highpass(10) or equivalently GaussBlur(10) - GaussBlur(20)?
Well, as true as PS will get you*. A more practical way to generate the band is to do the high-pass filter at the higher radius limit (e.g. 20) and then G.Blur the layer at the lower limit (e.g. 10)

Quote:
Originally Posted by SWEngineer
Sadly (for me), I only have Elements, so I can't play with your action file.
The action file is just a quick way of making up a whole load of bands. With a bit of practice you can estimate a good band and do the High-pass / GBlur trick above.

Quote:
Originally Posted by SWEngineer
This opens up an entire new dimension for selectively modifying images. In addition to tone & color, its obvious now that one can work with "frequency" with near equal ease.
Exactly

Quote:
Originally Posted by SWEngineer
...but mathematically inclined person...
*Then you're going to just love the FFT (Fast Fourier Transform) stuff!

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Old 01-07-2005, 06:50 AM
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thanks for an extremely interesting article

reminds me a bit of my first lectures in image processing, when i've been trying to figure out how to do USM in image domain w/o having to convert to spectral domain (FFT)... how trivial it is! and yet it took me few hours
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Old 02-04-2005, 04:48 PM
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Very sweet...

This has a lot of applications.. Awesome stuff especially masking related..
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Old 05-09-2005, 04:36 PM
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venivedi venivedi is offline
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Wow, cool. I'm so impressed by a layer named 'clipping'
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  #10  
Old 05-10-2005, 06:22 AM
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Quote:
Originally Posted by venivedi
Wow, cool. I'm so impressed by a layer named 'clipping'
Glad you liked it.
As I remember there is an action for setting up the layer in the ten-minute tool box - then you can use it anywhere.

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