Join Deke McClelland for an in-depth discussion in this video Enhancing clarity with the High Pass filter, part of Enhancing Underwater Photos with Photoshop.
- In this movie, we're going to enhance the clarity, that is to say, the degree of edge contrast using a filter known as High Pass and then we'll clean up some of the noise using the Reduce Noise filter. Now, because we're working with filters, we naturally want to be able to apply them as nondestructive, editable, Smart Filters so we need to convert the original image down here at the bottom of the Layers panel to a smart object so if you're working along with me, go ahead and select that moon jelly layer, and then armed with the rectangular marquee tool, which you can get by pressing the M key, go ahead and right click inside the image window and choose Convert to Smart Object.
And that will place the image into a special, protective container so we can't harm it for good. And notice, by the way, that Photoshop marks the smart object with a little page icon in the lower right corner of the thumbnail. And if you want big thumbnails like I have, incidentally, here inside the Layers panel, then you can right click in an empty portion of the Layers panel, that is below the bottom layer, and then choose Large Thumbnails from the list. Next, I'll go up to the Filter menu and choose Other and then we want to choose High Pass and that will bring up this dialogue box here, that by default, appears to just turn the image gray.
So for example, I'll click right about at this location inside the image window so that we can see these bright areas of the moon jelly. So, notice that we have a few different shades of gray going on here. What's really happening is that Photoshop is taking the non-edges inside the image, the areas where the pixels look pretty much the same in terms of their luminance levels and it's turning those regions gray and then anything that's in edge where the luminance levels change quite quickly, then those edges kind of hang on for dear life.
And this is gonna make more sense in just a moment. But first of all, a little bit of information about how High Pass works. If you want to sharpen the detail inside the image, then you want to go with the low Radius value, something like three pixels is pretty common. But if you want to enhance the overall clarity, that is the edge contrast, then you want to take this value much higher. And in my case, I went with a Radius value of 100 pixels and we end up with this fairly mysterious effect right there, at which point I'm going to go ahead and click OK to apply that filter.
Now, this effect is pretty cool I guess in so far as it goes, but it's not representative of the actual scene. We need to bring back the original colors and just as we did a couple of movies ago, we're gonna take advantage of the first and foremost contrast mode which is the overlay mode and to apply it, go down here to the High Pass filter which is now listed inside the Layers panel, and notice this little double slider icon over here on the far right side. Go ahead and double click on it in order to bring up the Blending Options dialogue box and then change the mode from Normal to Overlay and watch what happens on screen.
We get back all the original colors, but we also get all the clarity that's associated with that High Pass effect. And to see what that looks like, I'll go ahead and click OK and then I'll turn off this eye in front of Smart Filters so that we can see what the image looked like a moment ago before we applied High Pass. So these are the normal edges that the camera captured inside this image and these are the enhanced edges thanks to applying a large High Pass value combined with the Overlay blend mode.
Now, we don't need this filter mask right here. It's just cluttering up the panel so I'm gonna right click on this white thumbnail and choose Delete Filter Mask to get rid of it. Now, the other thing that's at work inside this image is noise and if I go ahead and zoom in by control space bar clicking, or command space bar clicking on the Mac, all the way into, let's say, 200 percent for the sake of this video, you can see that we've brought out a lot of noise. Notice if I turn off the Smart Filters, once again, this is what the image looked like without the clarity enhancement and this is what it looks like now and any time you enhance the clarity or sharpen the detail inside the image, you're going to bring out noise and in the case of this image, we have quite a bit.
To diffuse the noise, go up to the Filter menu, choose Noise and choose the Reduce Noise command to bring up the Reduce Noise dialogue box. Now, the default settings are all very well and good and incidentally, you're going to see the image before all the other stuff is applied to it, all the adjustment layers, here inside the dialogue box. Which means that this ginormous preview inside this dialogue box which so many people love, I don't, I'm not a big advocate because it's blocking the better preview, the more representative preview, out here in larger image window that takes into account all of those adjustment layers.
Now, what this is telling me out here is that these default settings are not doing us much good. We need to crank the strength value up to it's absolute maximum, which is 10. Then, I'm gonna take preserve details all the way down and then what you do is you just kind of bump it up by pressing the up arrow key until some of the noise starts to come back and we need to get to a point that it's tolerable which occurs to me at about five percent, then you leave it alone. Now, to really get a sense of what's going on here, take the sharpened details down to zero percent.
I don't know what it's doing at 25 percent by default because it's a very simple, and not particularly elegant sharpening effect. And then, I'm gonna take the Reduce Color Noise value up just a little bit to 50 percent, like so. Now, unless you want to overwrite the default settings, you want to go ahead and save off your own settings by clicking on this little hard drive icon and I'll call my new settings Big Noise and then click ok and next you need to switch the settings from Default to Big Noise so that you don't overwrite, once again, the default settings and then click OK in order to apply that filter.
And to get a sense of what we've done, I'll press Control Z or Command Z on the Mac. This is the original noise. I'll go ahead and zoom in just a little bit so that we can really see it there. And then if I press Control or Command Z again, that is the new and improved noise, thanks to the filter we just applied. Alright, now I'm gonna press ctrl 0 or cmd 0 on the Mac to center my zoom and just so we can get a sense of what we did inside this movie, I'll turn off the Smart Filters once again by clicking the eye in front of the words, Smart Filters. So this is that version of the image that we saw at the beginning of the movie and this is the image as it appears now thanks to a combination of High Pass and Reduce Noise applied as editable Smart Filters here inside Photoshop.
- Selecting the best frame of a fish in motion
- Correcting contrast
- Enhancing clarity
- Bringing out color and beauty in Camera Raw
- Sharpening a moving target with Shake Reduction
- Correcting lens distortion
- Developing black-and-white versions of underwater photos
- Creating a looping movie or animated GIF
- Framing macro shots
- Simulating depth of field with Gaussian Blur