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eliminating halos when sharpening for web


i briefly mentioned my sharpening method in the waterloo falls workflow that was posted a few weeks ago, but in this tutorial i’ll try to expand on it a bit further and include some side by side comparison images to illustrate the main problem that most of you have probably encountered in sharpening for the web: the dreaded halo effect. but first…

sharpening with the smart sharpen filter
i’ve ditched the unsharp mask in favour of the smart sharpen filter. if you’re currently sharpening with unsharp mask i’d suggest you ditch it too. with the smart sharpen filter you can save your settings and you can selectively sharpen highlights and shadows independantly thereby enabling you to apply more sharpening without producing crazy amounts of haloing.

that said, with some images you simply can’t avoid a bit of halo around those high contrast edges. i find that it’s not much of a bother except for where the sky meets the foreground.

so, in those cases where i can anticipate that halos will be a byproduct of sharpening i’ll duplicate my image layer and make sure that my duplicate layer is selected before opening the smart sharpen filter. you’ll see why later.

smart sharpen

above are the typical sharpen settings i’ll use for 99% of the images i’ll post to thinsite. set the Remove method to Lens Blur cause i think it does the best job of minimizing halos and tick the More Accurate checkbox because why would you want to be less accurate? the real power of the smart sharpen filter is in its ability to control shadow and highlight sharpening independantly so click that Advanced radio button cause you’re no n00b… you’re a photoshop champ. here are the two tabs as i set them for this particular image:

shadow tab highlight tab

this is where a bit of experimenting comes in. increasing the fade amount and tonal width reduces the amount of sharpening applied so slide around until you get the look you’re after. it’s easy to lose perspective so i click the preview checkbox on and off all the time and see what effect the sharpening is having on the workspace. in this case i was looking for a somewhat sharp effect to emphasize the grit and rust of the tank so i’m mostly unconcerned with the amount of haloing introduced at this point. go nuts.

removing the halos
so now that the duplicate layer is crispy sharp we’ve gotta remove those jaggy halo bits. simply grab your eraser tool and with a small radius and medium edge erase the halos on the duplicate layer thereby allowing the unsharpened original layer underneath to peak through. that’s it. there’s nothing more to it. here are the individual steps from this particular image to illustrate the process. the differences are subtle so you might have to look closely at where the coil meets the sky. in my opinion it’s these little details that you can easily incorporate into your workflow that make a world of difference.

original without sharpening
sharpened duplicate
sharpened duplicate layer
sharpened duplicate with halos erased
original and duplicate combined

a note on why sharpening comes last and only last
sharpening is an essential final step in the workflow of any image regardless of whether it’s going for print or web. this is especially true if you shoot in RAW where the camera will not apply any in-camera sharpening. however, when you process your RAW file your convertor will likely have a default sharpening setting. i’m a bit of a control freak so i don’t let my RAW processor apply sharpening. also, i’ll be resizing the image to fit for web so whatever sharpening applied at full resolution will likely be lost in resizing.

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