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Thread: High pass filter

  1. #1
    Alis's Avatar
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    High pass filter

    I have been lazy before, and I am going to do it again: Could someone please briefly explain to me what a high pass filter is and when it should be used and how to use it?

    Thanks,

    Alis

  2. #2

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    Re: High pass filter

    Quote Originally Posted by Alis View Post
    I have been lazy before, and I am going to do it again: Could someone please briefly explain to me what a high pass filter is and when it should be used and how to use it?

    Thanks,

    Alis
    Hi Ali,

    I'm a bit busy right now - but this site will help.

  3. #3
    Alis's Avatar
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    Re: High pass filter

    Thanks, Colin. I will read it.

  4. #4
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    Re: High pass filter

    Colin-
    This is a great tutorial. I use Corel, but the steps are pretty much the same! Another quick fix!
    Thanks!!!!

  5. #5

    Re: High pass filter

    And you can Invert it to blur.

  6. #6
    Alis's Avatar
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    Re: High pass filter

    It was very easy indeed. Here is the result of my quick attempt on it (of course the model remains the same :

    High pass filter

  7. #7

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    Re: High pass filter

    Well if you people like the effect of the high pass filter, I do, then you would absolutely drool over the sharpening setup in Lightroom.

    Without going into detail because it takes about 4 pages of a book to describe, but takes about 5-10 seconds to do. It basically uses the high pass filter system but simplifies/modifies/improves its use by using 4 sliders and the alt key, the alt key gives you the grey mask view in each slider so you can vary the adjustments to suit your style, and you have more control over what is sharpened and what is not, as opposed to just sharpening the edges. You can just sharpen the edges too.

  8. #8
    Alis's Avatar
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    Re: High pass filter

    Quote Originally Posted by Bill44 View Post
    Well if you people like the effect of the high pass filter, I do, then you would absolutely drool over the sharpening setup in Lightroom.
    Hi Bill,

    I am not sure if I liked it. I did the example I posted here last night as I was reading the instructions on that webpage and am not sure if I went to far or if I do it again I am going to get a better result, but looks like like anything else, when you make something easy, you lose control over details.

    What I am still not sure is if this is only used for sharpening or it has other uses. And for sharpening, I am suspecting it is better to use it in some situations and it does not work that well in others. In the example I posted, I had to undo some of the effect on the hair and it still does not look right but it somewhat worked on the eyes and rest of the face. So, I need to play with it more.

    By the way, I had seen the instructions on how to use this in lightroom in Martin Eventing's "tipbook" but at the time I did not pay attention and thought is some cool effect in LR.

    Alis

  9. #9

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    Re: High pass filter

    Alis, the major part of the control is the Mask slider. After you have used the top 3 sliders to do your sharpening the mask slider then controls what is sharpened and what is not. The most common problem I find is that a lot of Lightroom users don't even know to use the Alt key when doing their sharpening, or to do the sharpening at 1:1.

    EDIT. When you hold down the Alt key nothing will happen until you actually click on a slider to drag it.

  10. #10

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    Re: High pass filter

    I think that it gives a good result with high-frequency components, but I'd also be inclined to apply another pass to address low-frequency issues (eg 20-40%; 2 to 4 pixels) (USM).

  11. #11

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    Re: High pass filter

    Something I left out of my post, the sharpening I've been referring to is capture sharpening, export sharpening in Lightroom is another issue.

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