Join Tim Grey for an in-depth discussion in this video Enhancing detail with high pass, part of Photoshop Artist in Action: Tim Grey's Photo Optimization Techniques.
I've applied some adjustments to try to enhance the overall sort of dreary grungy look for this photo that I'd like to achieve in the final result, but I think I need a little bit more drama, a little bit more of an effect here. And so I want to apply essentially something of sharpening effect, it's really a local contrast enhancement, but it's very similar to a sharpening effect that's applied over a broader area. When we sharpen an image, we're essentially enhancing contrast among very fine edges. In other words, where there's a difference in pixel values we're adding contrast but just in a very small area. When we apply a local contrast enhancement, we're essentially doing the same thing Just over a larger area.
So each area that has some level of contrast will enhance contrast but that transition in terms of the area where the contrast is being enhanced will be significantly larger. Lets take a look at the technique that we'll use here. I'm going to start off by going down to my transformation layer. That's a layer that I used in order to straighten out the image, and I'm going to create a copy of that layer. That essentially is the actual image at this point. I still have my background image layer, which contains the original capture without the transformation, but essentially, the transformation layer now replaces it. So I'll go ahead and drag the thumbnail for the transformation layer down to the Create New Layer button.
The blank sheet of paper icon at the bottom of the Layers panel that will create a new copy, and I am going to double-click on the name of that layer and type a new name for it. I will call this Local Contrast and then press Enter or Return on the keyboard to apply that name change. Next, I am going to change the blend mode for this local contrast layer from the default of normal to overlay using the pop up at the top left of the layers panel. That will give us a bit of contrast but this isn't the final effect that I'm after.
To achieve that result I'm going to go to the filter menu and then choose other followed by high paths. And this filter will apply essentially and emboss effect to the image. Most of the pixels will become very close to middle gray which means they'll have no effect on the image since So we're using the Overlay blend mode. And 50 percent gray is the neutral color or the color that has no effect when it comes to using the Overlay blend mode. But the pixels that are lighter or darker based on that embossing effect will become lighter or darker in the actual image, so I'll go ahead and chose High Pass from the menu.
That will bring up the High Pass dialog. If I use a low radius, you'll see that we essentially get just a very subtle sharpening effect. If I drag up to a really large value, I'll get essentially an exaggerated contrast effect in the image. What I want is a somewhat moderate effect, I'll go ahead and drag around this preview and you can see that we're getting an embossed effect, at this level, it's not very obvious in this preview. I'll go ahead and reduce the values so that you can see it a little more clearly that overall the pixels appear medium gray, but some appear lighter and some appear darker Based from where the edges are.
So this would be the equivalent of a very basic sharpening effect but instead we're going to take that radio sub to a somewhat high value or a moderate value, in this case that will create a result that's closer to the original image but with a bit of contrast and you can see that in the photo That's giving us this sort of stylised local contrast effect, almost like sharpening but really just enhancing some of those details and giving us a little bit more drama. I'll go ahead and click okay in order to apply that effect, and then I'll turn off my local contrast layer and turn it back on again.
And you can see that we've achieved quite a bit more drama within the image. And more important in my mind, we've achieved a result where some of that grunge on the building, some of the accumulated dirt and soot, is darkened up a bit. The contrast has been enhanced so that those areas appear a little more clearer in the image. So at this point I have a pretty good effect, still not quite the final result that I'm looking for in this image, but getting much closer compared to the original photo.
- RAW conversion and processing
- Spot removal
- Cropping and straightening
- Adding local contrast
- Black-and-white conversion
- Correcting perspective with Transform
- Enhancing detail with High Pass
- Applying HDR tone-mapping
- Adding a custom vignette