Using high pass filter to achieve negative clarity

[Richard Liu]

I recently ran across this proposal for using a high pass filter in Photoshop to achieve the same results as negative clarity:  http://thegreyblog.blogspot.com/2011/11/clarity-adjustment-local-contrast-in.html .  In effect, the proposal is to "simply" invert the layer created by the high pass filter and overlay that on the original, this as opposed to not inverting the layer before overlaying it, thereby simulating the clarify filter.  I'm having some difficulty doing this in Affinity Photo.  I create a high pass live filter underneath the Background layer, set a radius that makes it evident where the local contrast is, and set the blend mode to Overlay.  Some details are sharpened, some are not.  Now if I invert the filter, nothing is affected unless I paint some areas with white, and then they will be sharpened, which is not negative clarity.  I'm sure I'm missing something very elementary here.  Can anybody tell me what?

[carl123]

On ‎7‎/‎24‎/‎2019 at 2:17 PM, Richard Liu said:

Now if I invert the filter

You invert the layer not the filter layer

[Richard Liu]

@carl123,

Yes, that's what I understood, but how do I do that in Affinity Photo 1.7?

Suppose I have a pixel layer containing an image, e. g. the Background layer produced by the Develop persona.  Now I add a High Pass live filter to it, typically as a child layer, set its radius and set its blend mode to Overlay.  So that's the high pass filter as it usually works.  Now to invert I go to Layer | Invert, but what layer do I want to invert.  Not the High Pass live filter layer.  That only leaves the Background layer, which I cannot select without selecting the High Pass one, too.  Presuming I duplicated the Background before beginning, do I then put the inverted Background cum High Pass live filter on top of the original Background and the blend mode of the inverted Background to Overlay?

[Murfee]

Hi @Richard Liu

You need to duplicate the background, add the High Pass Live Filter as a child of this layer, set the radius but leave the blend mode alone. Now change the blend mode of your duplicated background with its child layer to overlay and invert.

Edit: If you need a more extreme effect try changing the layer blend mode to Soft Light or even more extreme you can try Linear Light with a lower radius.

Edited July 26, 2019 by Murfee
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