Sharpening to remove haze/fog

[Robt]

A few years back, I read a column about using USM to clear haziness from an image.  My memory is that the article was written by Michael Reichmann on this site.  

Can anyone point me to the article I'm remembering?  I took what I learned from the article and made an action which I never backed up so when that drive failed, I now need to start over with the original because I used the info and find my old memory isn't as reliable as it once was.

BTW, I think the technique was USM at 20,50,0 play with it and the image was suddenly clear of haze.  

THX

[Richowens]

It is called Local Contrast Enhancement.

Tutorial page

 HTH

 Rich

[jgille]

The "Clarity" setting (Basic set) in Lightroom has the same effect.

Cheers

[walter.sk]

The "Clarity" setting (Basic set) in Lightroom has the same effect.

Cheers
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I think the Clarity function is at the top of the improvements in ACR.  However, I am not sure whether such increase of local contrast is best performed after resizing an image or should be considered one of the adjustments that is best done at the RAW stage.

So far, I use it on almost all of my RAW files, which are then converted at the native size into 16 bit tiffs for more work in CS3.  I use Qimage to uprezz and sharpen for final output, and I have not seen artifacts that I could associate with the early-stage Clarity adjustment, even in prints up to 24"x36".

[jgille]

I think the Clarity function is at the top of the improvements in ACR.  However, I am not sure whether such increase of local contrast is best performed after resizing an image or should be considered one of the adjustments that is best done at the RAW stage.

So far, I use it on almost all of my RAW files, which are then converted at the native size into 16 bit tiffs for more work in CS3.  I use Qimage to uprezz and sharpen for final output, and I have not seen artifacts that I could associate with the early-stage Clarity adjustment, even in prints up to 24"x36".
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What values are you using for Clarity in Lightroom ?
I am using Unsharp Mask with 20 50 0 in Photoshop most of the time.

Cheers

[walter.sk]

What values are you using for Clarity in Lightroom ?
I am using Unsharp Mask with 20 50 0 in Photoshop most of the time.

Cheers
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I shoot with a 1DMkII, and find that if my exposure is right, a setting of 30-50 on the Clarity slider does a great job. I don't use LightRoom, but do use the raw converter in CS3.

[Jack Varney]

You may have seen one of two other articles on haze removal and local contrast enhancement. At the time Michael wrote about local contrast enhancement I stumbled upon an article entitled "The Clarifier (Targeted Lecal Contrast Enhancement)". The article can be found here - http://www.lonestardigital.com/photoshop_quicktips.htm.

The article describes the same approach with somewhat different values for haze removal.

Lone Star Digital references Michael's article and another at Cambridge In Color which can be found here - http://www.cambridgeincolour.com/tutorials...enhancement.htm.

[Philmar]

As a digital noob I am confused by the Clarity slider in ACR. I have read Mr. Schewe's article about the changes to ACR and how to use the Clarity slider. It advocates judging it's application while viewing the RAW file at 100% view. But I never see any halos, even when applied liberaly (at least not to the extent that I see halos when I use the sharpening sliders at 100% viewing)
As a result, I usually back off the Clarity slider at around 10 (except with shots with lots of haze) out of fear of over-processing a shot.
Do people apply Clarity to most of their shots? How much? Yes I know it depends on the shot but are there any general rules of thumb? Are there types of photos (i.e. like hazy day shots, shot from a long focal length lens) that benefit more from Clarity than others? Are there types of photos where use of Clarity would be of no benefit?

[pflower]

I use Clarity from Lightroom fairly often, but in Photoshop the USM of 20-60-0 works pretty well and I also find that converting to LAB and a shallow S curve on the luminosity channel can often work wonders in cutting through haze.

[Paul Sumi]

As an aside, I have found that the Photoshop Shadow/Highlight tool can also sometimes reduce/remove haze.

Paul