How does opacity affect USM?

For example, assume I applied a USM filter with a value of 50, radius of 50, and threshold of 0, on to a duplicate layer.

If I then reduced the opacity of that duplicate layers to 50% what would the effect be?

Would it be as if I had applied USM using the settings 25/50/0, or 25/25/0, is there a different formula, or would it be an effect that could not be created any other way?

Michael.

Reducing opacity would be closely equivalent to reducing the Amount, I'd say.

That would be my instinctive thought too, but I am not certain and would like to understand what actually happens.

My reason for asking is from wondering whether it is okay to create an action that provides a high-ish level of USM for local contrast, then uses the opacity to set it to a suitable level for a particular photo.

Or would the results be too compromised that it would the only option is to manually apply USM on a photo-by-photo basis for local contrast.

Michael.

I'd say it's a viable option, as long as your images are all roughly the same size. Obviously the radius that works for a 12MP image won't work the same on a 3MP image.

If you were thinking of output sharpening (ie small radius) I'd be wary, because the Threshold would be too much of a factor; but for local contrast enhancement (ie large radius), where the threshold is usually kept very low for everything, it should be fine.

You might also try "High Pass Sharpening..."

Duplicate your finished image on a new layer
Go to FILTERS -> OTHER -> HIGH PASS
Select a pixel width of between .5 and 1.0
Then go to layers and make that HIGH PASS treated layer either an OVERLAY or SOFT LIGHT (depending on how strong you want the sharpening effect)

Play with the opacity to see how it affects the sharpness of your photo

Zoom to 100%, play with opacity, see for yourself.

You can also use the snapshot feature in history to save a few passes using different ideas, then flip back and forth to compare.

Just create 3 more layers. on the first copy layer apply your 50/50/0 and set to 50%. On the 2nd copied layer try your 25/25/0. On the top apply the 25/50/0. Then just toggle the top 2 layers on and off. Maybe over-exaggerate your sharpening a bit to see if there is a difference.

I have a high pass sharpening action that deliberately sets the sharpening too high. I then reduce the opacity to get good sharpening without those nasty halos. I don't see why the same wouldn't work with USM sharpening.

If you go experimenting, don't forget to also experiment with the "blend if" sliders

I think you can use the "fade" command to do that can't you. If done next step after sharpening. Not sure , its been long time.

Examples I have seen were landscape images globally sharpened , even on the heavy side, then faded to taste. Seemed to work nicely for that.

Chuck

freebird wrote in post #5611066
I think you can use the "fade" command to do that can't you. If done next step after sharpening. Not sure , its been long time.

Chuck

IIRC, that is a trick recommended by "Guru" Kelby as well...

And if it's good enough for him...

carpenter wrote in post #5608461
Just create 3 more layers. on the first copy layer apply your 50/50/0 and set to 50%. On the 2nd copied layer try your 25/25/0. On the top apply the 25/50/0. Then just toggle the top 2 layers on and off. Maybe over-exaggerate your sharpening a bit to see if there is a difference.

I did just that, and all three gave different results.

Even adjusting the opacity level, in case it was not such a simple linear scale, I could not get it to match either of the other two. So it is clearly doing something different.

As it seems no one else has used this method I will have to find the time to try both approaches and see which comes up with the best results overall.

Michael.