Join Tim Grey for an in-depth discussion in this video Improving local contrast, part of Restoring Photos with Photoshop CS6.
With many images that you restore you're likely going to want to enhance detail to some degree. And that might cause you to automatically think about sharpening the photo, but with many older images there simply isn't enough detail to apply sharpening effectively. Instead, I'll tend to use a technique that I refer to as a localized contrast enhancement. It's very similar in concept to sharpening. But it applies across a broader range of pixels. And so it enhances overall contrast without causing some of the problems that you would might run into with sharpening. The first step is to create a composite layer.
I want to retain all of my layers. You can see here that I have a layer for vignetting, an image clean-up layer. As well as the curve's adjustment layer, but I want to create a new layer that reflects all of these layers in a single layer, so that I can use that as the basis of my adjustment. So I'll click on the top layer, in this case the curve's layer on the Layers panel. I'll then hold the Control, Alt and Shift keys on Windows or the Command option and Shift keys on Macintosh and then hold those keys while I first press the letter N and then press the letter E. That will create a new layer and then it will perform what's called a Stamp Visible Command.
So that the contents of that layer are filled with the composite of everything below. In order to stay organized, I'll go ahead and double-click the name for this layer, and I'll just call it composite, and then press enter or return once I've typed that new name. I can then apply some adjustments to this layer in order to enhance detail and contrast in the underlying photo. The first step is to change the blend mode for this composite layer from the normal blend mode to overlay. This is a contrast blend mode, and as you'll see, it immediately creates some contrast in the photo.
Not good contrast, mind you, but contrast nevertheless. We're now going to use this blend mode in conjunction with a filter in order to enhance detail in the photo. In effect, what we want to do is emboss the composite layer so that that overlay blend mode is adding contrast just along the edges. So I'll go to the filter menu and then choose other followed by high pass. Generally speaking, I'll start out with a setting of about ten pixels for most images. That will usually give me a good degree of contrast.
But the right setting will vary based both on the overall detail in the image. As well as the overall resolution of the photo. You can see the sort of embossing effect in the preview here. With this image, it's a relatively low resolution image, and so I'm going to use a small radius, somewhere around five pixels will probably work out pretty well for this photo. I can also see in the image itself the effect, and I have a little bit more enhancement of detail. In effect, the photo looks like it was captured a little more sharp.
I'll go ahead and click OK to apply that high pass filter, and then I'll turn off the visibility for that composite layer and turn it back on. You can see the effect is relatively subtle. I'm not looking for an exaggerated sharpening effect. I don't want the image to look artificial. This is an old photo. It's a little bit soft, but I want to enhance the detail as much as I can without causing any harm. And this process of enhancing localized contrast can really be very helpful. So working with a composite layer using that overlay blend mode, and then applying the high pass filter, you can see it gives me a real improvement in terms of the perceived focus of the photo.
- Choosing your source image
- Adding metadata
- Image restoration strategy
- Working with layers
- Evaluating before and after
- Tonal and color adjustments
- Image cleanup
- Adjusting detail
- Saving the master image
- Creating a print or online version