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Sharpen Your Digital Photos with the Unsharp Mask
Posted by Adam Pash at 6:00 AM on May 28, 2008
Photography web site Photojojo details how to get crisp, beautiful prints from your digital photos with Photoshop's Unsharp Mask. What's the point of sharpening, you ask?
Digital cameras have a fixed grid of pixels, each of which can only capture one colour or shade at a time. Say you take a picture that has a sharp edge between black and white... The single pixel that records that hairline edge can only record one colour, so it renders it as grey. What we think of as sharpness is actually the contrast we see between different colours. A quick transition from black to white looks sharp. A gradual transition from black to grey to white looks blurry.
A little time with the Unsharp Mask, though, and you can lose the blur along the edge of colour transitions and bring more sharpness and fidelity to your photos, and Photojojo's guide is an excellent starting point. If you're an expert Unsharp Mask-er, let's hear your tips for making the most of the tool in the comments.
Comments (AU Comments · US Comments)
There are currently no AU comments for this post.
ramthor
Posted 1:34 AM 29/5/08
>>Unsharp Mask really. What are we using Photoshop 7?
Actually, mein freund, some of us old timers are still using Photoshop 6. Works quite well for hobbies and recreational use. Not to mention saving several $100's for CS upgrade. Cheers.
ramthor
FotoVerite
Posted 2:16 PM 28/5/08
Old Photo Film Technique back when photographers where real women/men and not digital technicians with fancy see before you shoot equipment.
Basically all it is a " a blurred (unsharp…) version of the negative" which is then sandwiched in the enlarger with the original negative.
FotoVerite
fadecomic
Posted 1:44 PM 28/5/08
What is the origin of the name "Unsharp Mask"? It seems counterintuitive to me. You're using an "Unsharp" mask to "Sharpen"?
fadecomic
hansning
Posted 1:27 PM 28/5/08
i've just started working in the digital darkroom, and one of the first things i learned is the high-pass filter sharpening method. i didn't even get a chance to explore the other ones really...
here's a link to a simple tutorial:
[nyfalls.com]
and a much more advanced one
[www.adobe.com]
i personally use radius of 4.0, and set the sharpen layer to soft light, but you have so much control using this method. note that this method REQUIRES huge images to work with, or else it'll create halos.
hansning
iheartbeer
Posted 11:18 AM 28/5/08
@Steve Hollasch: CS1 doesn't have Smart Sharpen, it must have shown up in CS2. So, thanks for the LAB suggestion!
iheartbeer
qbix
Posted 10:08 AM 28/5/08
Smart Sharpen for me too. Does anybody sharpen in RAW edit mode?
qbix
phrancis
Posted 8:53 AM 28/5/08
Yeah, smart sharpen all the way...
phrancis
FotoVerite
Posted 8:08 AM 28/5/08
@bdjohns1: However, there is still one good use for USM - local contrast enhancement (ie, haze cutting). Try a large radius (40-60px) and a low amount (30-50%) - it does wonders for cutting through some of the afternoon haze in landscape shots.
Thanks for the tip on use for USM.
FotoVerite
bdjohns1
Posted 6:55 AM 28/5/08
Agree with Steve - if you're using a legacy version of Photoshop (pre-CS) or some other image tool, sharpen in Lab color on only the L channel if possible - this avoids amplifying noise in the image. (another good trick in Lab mode is to use a curve to steepen the slope of the a/b channels to enhance color contrast)
If you've got PSCS/CS2/CS3, there's not a good reason for using USM for general sharpening work - just use Smart Sharpen and be done with it. However, there is still one good use for USM - local contrast enhancement (ie, haze cutting). Try a large radius (40-60px) and a low amount (30-50%) - it does wonders for cutting through some of the afternoon haze in landscape shots.
bdjohns1
FotoVerite
Posted 6:52 AM 28/5/08
Unsharp Mask really. What are we using Photoshop 7? Smart Sharpen all the way.
Better algorithms plus preview area.
FotoVerite
sc8tty
Posted 6:44 AM 28/5/08
Gotta agree with Steve. I only use Unsharp Mask these days for complicated edge masking techniques. Smart Sharpen takes care of all my general sharpening needs.
sc8tty
Steve Hollasch
Posted 6:39 AM 28/5/08
The best way to use the unsharp mask is to switch to Lab mode (Luminance/A/B) in order to avoid color artifacts. Then select the luminance channel and apply the unsharp mask there. I typically sharpen 150% - 200%, and have learned to fiddle more with the pixel radius than with the percentage. When you're done, switch back to whatever color space you like to work in.
All that said, I abandoned this method once Smart Sharpen came out (Photoshop CS1). Smart Sharpen does all this and more and better, in my humble opinion.
Steve Hollasch
kyle5434
Posted 9:45 PM 29/5/08
I use - and am still happy with - Photoshop CS. For those with a version of Photoshop before CS2 - or any other app that can use Photoshop plugins - there's a great plugin, which pre-dates Adobe's Smart Sharpen, called FocalBlade. It basically does the same thing - intelligently sharpening areas of the photo based on local contrast, the photo's pixel dimensions, and whether you want to sharpen for screen or print output. I've found that setting it for Edge Sharpening, Medium Details, works 95% of the time for me.
Of course, for serious no-fuss PRINT sharpening, nothing beats Qimage.
kyle5434
kevbroch
Posted 11:37 PM 30/5/08
Also available in the GIMP: [docs.gimp.org]
kevbroch
mconheady
Posted 3:51 PM 3/6/08
@fadecomic: @fadecomic:
In the darkroom days, people would make a blurry copy of the print and use it as a mask. The blurred copy would have lines that extended beyond the lines of the sharp print- because the blurry lines are thicker. Then the negative and mask were combined and the overlap of the blur over the sharp created halos around lines in the final print, making them look sharper.
Unsharp mask is old and causes halo-ing. High-pass is the way to go to retain detail: [www.nyfalls.com]
mconheady