Join Tim Grey for an in-depth discussion in this video Image sharpening, part of Photoshop: Raw Workshop (2013).
One of the more interesting things about sharpening with digital photographs is that if it's very obvious an image needs to be sharpened, there's probably no point sharpening it because you're not going to salvage an out of focus image. And if an image appears sharp, you probably do want to apply sharpening in order to compensate for the subtle loss of sharpness that can occur with a digital capture. In other words, even if you don't think you need sharpening, it's probably a good idea to apply some. And in fact in the Raw conversion process, we can apply some basic sharpening that is aimed not at creating a final image but, rather, on compensating for the factors that cause a loss of sharpness in the original capture.
For example, most digital cameras include an anti-aliasing filter on the front of the image sensor. And that filter serves to minimize or eliminate the risk of Moire patterns, but it also softens the image a little bit. And even just the process of converting analog light information into digital values causes some loss of sharpness. Fortunately, we can compensate for that loss of sharpness during the raw conversion process in Adobe Camera Raw. To get started, I'll click on the Detail button.
That's the third button on the row of buttons below the histogram in order to switch to the detail controls. And in that detail section, we'll find the controls for sharpening. We have an Amount slider that controls the intensity of the effect. We also have a Radius slider that determines how large of an edge we're creating in our images. In other words, when we sharpen or enhancing contrast along edges in the image, and the radius value determines how large an area we're going to enhance with that contrast, we can also specify how much detail we want to enhance.
In other words, do we want to enhance every little nook and cranny in the image or just the larger detail areas? And finally, do we want to focus our sharpening only on the real edges in the image? So, for example, do I want to only sharpen along the outer edge of this burrowing owl or do I want to sharpen all areas of the image? Of course, having a basic understanding of those controls is all well and good. But it can be more helpful to get something of an enhanced preview of the effect. And to do that you can simply hold the Alt key on windows, or the option key on Macintosh while you're adjusting the individual sliders.
So I'll hold the Alt or Option key and then adjust the amount and you'll see that while I'm making this adjustment, the image is transitioned to a black and white preview, so that I can better see the effect of the actual sharpening without being distracted by color. Of course, you'll see that the effect is relatively subtle, and that's by design. The sharpening controls in Adobe Camera Raw are aimed at compensating for the loss of sharpness in the capture, not creating a final print. But if we increase the value for Radius, for example, then that amount will be a little bit more obvious within the photo.
You can see as I drag to the left, the image looks almost a little bit more soft. And as I drag over toward the right it starts to look almost a bit crunchy. We've got quite a bit of enhanced texture in the photo. Let's take a look at the Preview option for the Radius control. I'll once again hold the Alt or Option key and as I adjust that radius you'll see that we can start off with a low value where we're affecting a very small area, in terms of the edges within the photo. But as I increase the radius, you'll see that that sort of embossed effect gets larger and larger. Now, the radius is limited to a maximum value of 3 pixels in Adobe Camera Raw. And so, even if we take it to that maximum, we're still not affecting a huge area of the image.
But in general, with high detail images, you'll want to use a relatively low radius and a relatively high amount. With relatively low detailed images, where the transitions and tonal values happen across a larger range, you'll want to use a relatively high radius with a relatively low value for a mount. So, in this case I might use a relatively high value for a mount and a relatively low value, something probably a little bit below 1.0 for the radius control.
But I can also control the overall range of pixels being affected. Let's take a look first at the detail slider. I'll hold the Alt key on Windows and the Option key on Macintosh, and you'll see that I get a similar preview compared to the Radius preview. But here I'm actually controlling the level of detail that is going to be enhanced. So not the size as it were, of that sharpening effect, but rather the degree to which I'm effecting fine detail. In this case, that mostly means the feather detail of the owl, so you can see with the high value I see lots of feather detail in this preview and with the low value you'll see some of that detail fade away.
And this preview gives you a sense of exactly which details will be enhanced by sharpening. In this case, since the focus is on the feathers, I'll go ahead and use a relatively high value. I think right about there will work pretty well. And then finally we can take a look at masking. I'll hold the Alt or Option key, and then, increase the value for masking. And as I do so, you'll see that the preview goes from all white to mostly black. The white areas indicate areas of the image where sharpening will be applied. And as I increase the value for masking, you'll see that most of the image is black and only the highest contrast edges throughout the photo will actually get enhanced.
So if, for example, it was very important to me to maintain the smooth textures in the background, then I might use a relatively high value for masking. If, on the other hand, I wanted to enhance every little nook and cranny throughout the photo, then I might use a relatively low value for masking, or even a value of zero. In this case though, I would like to preserve some of that smooth detail, and so I'll increase the masking to a moderate value. Something right about like that should work pretty well. And of course, now that I've scaled back that sharpening to only affect the highest contrast areas in the image I can probably get away with higher values for amount and possibly for radius.
But one of the most important things when it comes to evaluating the results of sharpening, is that you should evaluate the image at a 100% Zoom setting. Here, we've been viewing the overall image so that we can get a better sense of how these controls affect the sharpening. But now that I'm ready to finalize the effect, I'll switch to a 100% View, and then use the Hand tool to pan to an area of the image that I want to analyze in particular. You'll notice for example at the moment my settings are a little bit too strong,and so I can reduce the amount value.
I can adjust the overall value for radius. And now that I'm zoomed in, of course, you can get a much better sense of exactly how I'm affecting the image. But I think the biggest issue here is I need to reduce the value for detail. That will help make sure that I'm only enhancing the real detail as it were within the photo. I'll tone down that amount just a little bit more and maybe increase masking just a little bit. I can still use that Preview option to get a better sense to exactly where I want to focus my sharpening.
I think right about there will work pretty well. I'll turn off the Preview and then turn it back on again and you can see the effect is relatively subtle. But I'm getting an improved level of detail within the photo Just by fine tuning those sharpening settings. So evaluating the image at 100% and really scrutinizing the settings, as you zero in on the best settings for a particular image, will help ensure that you have the best starting point in terms of overall sharpness.
- Opening raw captures
- Setting Camera Raw preferences
- Zooming and panning
- Processing multiple images
- Image rotation, cropping, and straightening
- White balance and tonal adjustments
- Sharpening and noise reduction
- Split toning
- Compensating for lens vignetting
- Focused adjustments