Post Processing » Sharpening 101 - Part 2
In my previous article on this topic, Sharpening 101, Part 1 we delved into what sharpening is (contrast) and why we need it (the nature of digital image capture and shaky hands). I discussed the three levels of sharpening I use in my own workflow:
(1) capture sharpening, to counteract the softening that occurs during image capture
(2) creative sharpening, such as retouching the eyes in a portrait
(3) output sharpening, which is dependent on how the image will be viewed, for example on screen, in the newspaper or on a museum wall
When is Sharpening Necessary?
Before I go into specific techniques let’s talk about our sanity. Do I follow this workflow for every single image I shoot? Heck no. It is not that I don’t enjoy sitting at my computer at 3 AM with a box of sugary cookies and an energy drink, obsessing whether to sharpen in LAB mode or use a High Pass filter, but believe it or not all of my images don’t deserve that much attention. I have so many students who want every image they shoot to be perfect, and truth-be-told, that is neither possible, nor necessary. This is why we edit. Not every image needs or deserves the full work-up. I shoot for a fairly broad range of clients - food, architecture and portraiture for magazines and newspapers, events for non-profits, weddings, and my own personal fine-art work. Not to mentioned the odd shot at a party or gathering of friends. If I am shooting a corporate event, I want to do as little post-production work as possible. Much of what I am shooting is candids and posed group shots. More times than not the clients want the images ASAP to post on their websites or to drop into newsletters. If this is the case I will set the camera to Auto and set sharpening to medium. This way I can do a quick edit on site at the end of the event, hand them a CD and hopefully walk away with a check in my hand. Every camera is different and you will need to learn the strengths of your own camera’s sharpening algorithms through experience. Just like in the old days of darkrooms, too much time spent in post-production means less time shooting, where both the fun and the funds are.
|A screenshot of the Adobe Camera Raw Dialogue Window displaying my original image.|
Truthfully the majority of what I shoot is going to need a bit more work than my corporate gigs and when that is the case I shoot RAW and turn off all sharpening in my camera. Even when shooting images that I know are going to require more attention, I try to batch process wherever I can. In other words, I try to apply adjustments to all the images I can at first and then work with individual images later. I edit my images in Adobe Bridge, (part of Photoshop CS and Elements). For example, on a portrait shoot of a judge for The New York Times I had the subject for 20 minutes. I shot about 125 pictures in two separate locations. By the time I finished two editing passes I had narrowed the potential images down to about 35 (keep in mind that every editor is different, some like many choices while others want a minimal number. Almost all of them will get a little testy if you don’t learn their preferences). I shoot in RAW for all of my assignment work and bring the images into Adobe’s Camera Raw (ACR) plug-in for CS5.
|Screenshot from ACR with the Detail tab highlighted.|
I use the ACR plug-in for the majority of my image editing, from exposure control to cropping to sharpening for capture. The controls for sharpening are found in the Detail tab to the right of the main window. In CS5 there are 4 sliders for sharpening and 5 sliders for noise control. We will focus on sharpening in this article. The top two sliders control how much the sharpening effect is applied and where it is applied. With all the sliders if you press the Alt/Option key as you click on the sliders you are given a grayscale/black & white preview to see exactly where the effects are being applied.
|Screenshot showing the Amount adjustment in the Sharpening tab.|
The four sliders are:
Amount, controlling how heavily the effect will be applied to your image.
|Screenshot showing the Radius adjustment in the Sharpening tab.|
Radius, controlling how many pixels out from the point of contrast to which the effect will be applied (another way to think of it is how big the sharpening halo will be on the edges of your images, too much and things look wonky.)
|Screenshot showing the Detail adjustment in the Sharpening tab.|
Detail, pulling back on the halo effect (kind of like putting the reins on the effect), lower settings mean less detail is sharpened, while higher settings pile it on, adding quite a bit of texture.
Masking, reducing the sharpening effect over the entire image.
A setting of 0 applies to the entire image, while a setting of 100 applies it to the edges. There is no golden ratio to apply with the sliders and depending on the subject, portrait vs. landscape, you will use different settings. With landscape work you probably want all of the fine detail to pop in the trees and natural formations, so you might use a heavier hand with Amount, about 50-70. With portraiture you want detail in the eyes and lips but you need to be careful that you don’t turn your subject's skin into a Martian landscape. My fine weathered judge had plenty of life gloriously etched into his face. I did not want to lessen this at all but, if you look at the grayscale preview in the Radius and Masking screenshots you can see how sharpening was being applied to his pores. By kicking up the Masking to 90, I was able to limit the sharpening to the stronger lines on his face, thus holding onto the great character in his venerable visage.
|The white area is where the sharpening will be applied, the black area will be masked.|
|Compare these 2 images to see how increasing the Masking can limit sharpening so that contrast is not too great.|
When shooting vanity portraits you want to be extra careful about how much detail you let into the skin. If I am shooting for a magazine or a personal client I can go even further with softening and tweaking the skin so that it glows like a baby’s bottom. When you shoot for newspapers you aren’t allowed to use any heavy retouching, as it is considered unethical. Actually 'Photoshop' is almost a dirty word in the photojournalism world.
|Screenshot showing Workflow options highlighted.|
|Screenshot showing Workflow options highlighted.|
For the judge shoot I needed to turn it in by deadline ASAP, so I knew I wouldn’t have time to do any further sharpening in Photoshop. I clicked on the Workflow dialogue options at the bottom. Here I can control the color space, image size and also apply sharpening as well. While not as desirable as working in Photoshop for expediency I set the sharpening to Matte standard. When your images run in newspaper there is a much larger need for sharpening, due to the way the paper absorbs the ink, this is called dot gain. Through experience I knew I would be safe with these settings.
|The final product, tearsheet from The New York Times.|
After all this work I felt sure I had a cover shot above the fold. In the end the picture ran deep on the inside, below the fold and in black and white!