UPDATE, JUNE 2024: Strobist was archived in 2021. Here is what I am up to now. -DH


After the Light: High-Pass Post Production

Let's get one thing straight first: I am no Photoshop wizard. I learned at the paper to use it sparingly, and my goal is always to do most of my work in-camera.

But a lot of people have asked about some of my post techniques, so I wanted to share one of my favorites. It's quick, easy and adds a cool, controllable look to your photos. And it mixes especially well with photos that have been lit.

People use high pass in a lot of different ways. And really, the high-pass filter itself is just a step in the process that ends with the combination of two layers. High-pass has a bad name because a lot of people go way over the top with it. But in moderation it adds a nice edge -- and it can be used to give a uniform look to a series of otherwise disparate photos.

Here is how I do it.

Here is a pretty straight (i.e., no high-pass) photo of baritone Steven Eddy, whom I photographed last year for the Howard County Arts Council.

One light source -- very straightforward stuff. It's lit with an White Lightning and an Octa soft box, against an out-of-focus sunset in a forest.

This is a "before" photo. And you'll notice the differences in the "after" photo (up top) are pretty subtle. More on that later. My goal is to add a little bit of a pop to this photo, with a little more control than if I just used curves.

First, I am going to create a duplicate layer of the photo in Photoshop. You can do this in the Layers menu, or (on a Mac) with CMD 'J'. You now have two identical photos, sitting on top of each other. Bear in mind that you can only see the top one right now.

Next, we desaturate the top layer. You can do it with your Hue and Saturation adjustment, or go to Image-> Adjustments -> Desaturate.

Now, you are looking at a B&W version of your photo -- which is sitting on top of an unseen color version.

Next step is to apply the high-pass filter. This is a slider, and there is some preference involved as the slider will have a lot of control over the final look.

I tend to hang out around 80 in the radius, and that number is a function of your file size. I shoot 12MP photos, which means ~4k dots on the long side. If you shoot larger or smaller files, adjust your radius proportionally. And again, this is an 'add salt to taste' thing.

Here is what your pic will look like now.

Remember, you are adding high pass to the top, B&W layer. But there is an unchanged color layer underneath that you cannot see right now.

Next, we are going to combine those layers in the layer palette.

By default, the opacity slider in your layers palette is probably set to 100%. That means you are viewing the top layer -- a B&W, hi-pass filtered layer -- with no transparency at all.

Let's combine the two layers. Under "layers" dropdown in your layers palette, combine them by choosing "hard light".

You'll get a photo that looks very Nike/Gatorade ad-looking, which is IMO way, way too much.

Take your opacity slider and bring it from 100% to 0%. You'll see your original photo appear again, as the top, combined/HP'd layer disappears.

Now, crank your opacity slider up until you get the look you want.

Here is the photo from the top of the post again, which is pretty subtle as I only took the opacity slider to 35%. (I tend to hang out in the 25% to 50% neighborhood, depending on the lighting style and subject matter.)

My preference is to use it at a level to where it is almost not there. I like to bring it down to zero, the slowly slide it up until the look starts to get just a little too strong. Then I back it off a bit.

Flatten your image to lock it in and you are done.

Some Considerations

Is this 'destructive,' as some Photoshop folks will surely complain? Yes, it is.

And I don't care. It is a quick technique, and I will have already saved a toned, dust-spotted version before I add high-pass.

Are there other ways to do it? Certainly, but this is mine.

You can find other techniques by Googling "high-pass filter" and photoshop. Go crazy.

Can you go to far with this? Oh, yeah.

And that's when photos all start to look the same. I like to crank it up until I can tell it is there, then back it off a tad.

If you a newspaper shooter, it occurred to me long after the fact that this might be a good technique to make your photos (especially sports pics) better survive the repro process.

The technique adds midrange contrast, tames highlights and shadows and loses a little saturation. And that's tailor-made for many crappy offset newspaper presses that print on Charmin.

If you want to know more -- including a version with more steps that gets you to a more specific look, I recommend checking out Dustin Snipes' excellent tutorial. He cranks it up a little (okay, a lot) more than I do, but he gets a cool look that works well in the context of his sports portraiture.


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