Even with good equipment, D700 and 500mm lens, my bird images suffer from sharpening halos whether prepared for the web using "Adamus" method,or print using smart sharpen in PS, or Nik sharpener 3.0. I don't apply sharpening until the final step of my work flow. With the advent of CS5, is there a way to use refine edge to more easily eliminate the halo and still have reasonable sharpness?
If you're getting halos, you're sharpening too much or at too high a radius. Both are likely in response to the image not being sharp enough on its own; it really shouldn't need aggressive sharpening. I rarely go over a radius of 0.2-0.3, except if things are really bad and I'll try a higher radius sharpening layer and only mask it in where absolutely necessary. Try using masks to sharpen just the specific places you need to.
"Smart Sharpen" rather than any of the other methods in PS can help as well. It uses "pinning" which will attempt to maximize the edge contrast without going beyond the tones of the surrounding pixels, which is the cause of halos. If you're still getting halos and want to sharpen more, a selection, as you mentioned, would be in order. I haven't used CS5 so can't help you there
One thing I found helpful is to sharpen on a layer. Make a copy of the background layer and set it's blending mode to 'Luminosity'. Next, apply your usual sharpening workflow to this layer.
My understanding is that that using the 'Luminosity' channel affects only the edge contrast, and does not affect the color. This could help reduce halos, as well as preserve color.
Ditto what Preston says.
Sharpening the Lightness (or Luminosity) channel on a separate layer keeps that effect away from the colors and helps reduce artifacts and other nasties.
I also select what I want to sharpen and then contract & feather the selection by one or two pixels. Then Layer->Layer via Copy, sharpen and change the blend mode from Normal to Luminosity as Preston outlined.
This definitely eliminates haloes and, after all, there's rarely any reason to sharpen the sky or extraneous features anyway.
Be sure to save that selection for later use during web sharpening.
Floris, what are all of your USM setting (amount, radius and threshold)?
The reason I ask is that amount and radius run opposite to each other and and you really can't state one without the other to put it into context. My default settings are Amount = 180, radius = 1.4 for digital capture and 0 for threshhold. This is a high radius but a low amount. And these numbers change a lot depending on the needs of the image.
Hank is running the opposite direction, with 500/0.2/0. Both will produce similar results but in a different way (wait - didn't he post - I thought he did but I am not seeing it as I proofread ). Neither is wrong.
(Edit: wrong post - Hank's reply is for a different message, the one below.)
Dan - Most of my sharpening is done at 0.2-0.3 px and on the order of 500%. My rational is, I want to sharpen the finest details, and as long as the noise isn't an issue, 0.2 radius sharpening really crisps up those details without making it look artificial. You do get a similar effect at a larger radius and lower amount, but it doesn't look quite as natural IMO. In the end, it's better to undersharpen than to oversharpen.
Has anyone tried LAB mode, copy layer, lightness channel, unsharp mask amount 500, radius 1.0 to 1.5, threshold 0. Apply the background lightness channel in darken mode at around 50%. I use CS4 it seems to work for me. Read it in a book by Dan Margulis a few years ago. I would think same moves are available in CS5.
I've done that method and it works well. I'd have no problem recommending it with the following qualification: I think David's main issue is in understanding the process of sharpening in general. Halos should not be appearing as a result of the sharpening process and if they are, something is being done wrong. Switching to LAB mode kind of hides the underlying issue and if we can solve that, your suggestion is a powerful alternative tool.
Where are you seeing halos? I'll generally see them when a dark region is next to a light region and especially if both regions are evenly toned (think a dark stick against a blue sky).
Also, would you mind posting an image (crop is fine) with your sharpening setting or technique listed step by step? Walk us through a "typical" problem image and maybe we'll see something in your workflow or settings.
One thing to bear in mind is that halos can also result from causes apart from sharpening. For example, let's say you have a dark foreground against a lighter value sky and you select the foreground with feathered selection. Next, you use a curves layer (or another method) to lighten the foreground. If the adjustment includes part of the sky, a halo will result because you've also lighened part of the sky.
If we then sharpen the image without correcting the halo, the effect is exacerbated.
Discussion
13 repliesMy understanding is that that using the 'Luminosity' channel affects only the edge contrast, and does not affect the color. This could help reduce halos, as well as preserve color.
--P
Sharpening the Lightness (or Luminosity) channel on a separate layer keeps that effect away from the colors and helps reduce artifacts and other nasties.
I also select what I want to sharpen and then contract & feather the selection by one or two pixels. Then Layer->Layer via Copy, sharpen and change the blend mode from Normal to Luminosity as Preston outlined.
This definitely eliminates haloes and, after all, there's rarely any reason to sharpen the sky or extraneous features anyway.
Be sure to save that selection for later use during web sharpening.
The reason I ask is that amount and radius run opposite to each other and and you really can't state one without the other to put it into context. My default settings are Amount = 180, radius = 1.4 for digital capture and 0 for threshhold. This is a high radius but a low amount. And these numbers change a lot depending on the needs of the image.
Hank is running the opposite direction, with 500/0.2/0. Both will produce similar results but in a different way (wait - didn't he post - I thought he did but I am not seeing it as I proofread
(Edit: wrong post - Hank's reply is for a different message, the one below.)
I've done that method and it works well. I'd have no problem recommending it with the following qualification: I think David's main issue is in understanding the process of sharpening in general. Halos should not be appearing as a result of the sharpening process and if they are, something is being done wrong. Switching to LAB mode kind of hides the underlying issue and if we can solve that, your suggestion is a powerful alternative tool.
Where are you seeing halos? I'll generally see them when a dark region is next to a light region and especially if both regions are evenly toned (think a dark stick against a blue sky).
Also, would you mind posting an image (crop is fine) with your sharpening setting or technique listed step by step? Walk us through a "typical" problem image and maybe we'll see something in your workflow or settings.
Lin
If we then sharpen the image without correcting the halo, the effect is exacerbated.
--P