Photoshop: Smarter sharpening with the High Pass filter
In previous posts I have introduced the basics of sharpening in Photoshop and I also looked at a way to spot sharpen an image in Photoshop Elements using faux layer masks. In this post I want to show you the benefits of using high pass sharpening in Photoshop as an alternative to using the Unsharp mask (click to enlarge some images in this post).
The Unsharp mask has historically been the sharpening tool that most Photoshop users start out using. There are, however, different and better tools to use and one of these is the High Pass filter. One reason for this is that the Unsharp mask operates on the actual image pixels and it makes changes to those pixels. The sharpening process that makes use of the High Pass filter doesn’t operate on the original image so it does not destroy the image pixels – this is particularly useful if you’re using Photoshop CS2 or earlier which doesn’t offer the Smart Objects for Filters option for applying the Unsharp mask filter.
In addition, instead of sharpening the entire image as the Unsharp Mask does, using this High Pass filter process limits sharpening to the edges in the image which is where the most value can be obtained from sharpening the image.
Step 1
To see the process at work, open an image and duplicate the background layer of the image. If your image has multiple layers, add a new layer at the top of the layer stack, click it to select it and press Ctrl + Alt + Shift + E (Command + Option + Shift + E on the Mac) to fill the top layer with a flattened version of the image – without affecting the other layers.
Step 2
In the Layers palette set the blend mode of the new top layer to Overlay. This will let you see the sharpening results in place on the image in the next step.
Step 3
With the topmost layer still selected, choose Filter > Other > High Pass. This filter has one slider to adjust the Radius value. Drag the slider until you see a pretty much gray image in the preview window with the only detail being around the edges of objects in the image. If you can see color in the preview image then the radius is set too high. Typically a Radius value of well under 10 pixels should be sufficient – we used 2. Click Ok.
Step 4
The image is now sharpened – check the original against the sharpened version by clicking the Layer Visibility Icon for the top layer on and off to compare the result.
To finish the effect, adjust the Opacity of the top layer to 0 and then move it back up stopping when you have a good sharpening result. The ideal Opacity will depend on your personal preference.
If desired you can use blend modes other than Overlay, for example Soft Light and Hard Light can be equally as effective depending on the result that you are looking for.
Tip
When you are sharpening an image, adjust the image to the way you want it to look if you’re planning to display the image on the web. If you’re printing it you can (and should), sharpen more aggressively.
If you are using Photoshop CS3 or CS4, before you apply the High Pass filter to the top layer of the image, convert it to a Smart Object by selecting the layer and choose Filter > Convert for Smart Filters. Then apply the High Pass filter to the new smart object in the same way as I have outlined above. When you apply a filter to a Smart Object you can return later on to edit it – simply double click the filter name in the layer palette and the filter dialog opens allowing you to change the Radius value.
Tags: Photoshop, Sharpening
26 Responses to “Photoshop: Smarter sharpening with the High Pass filter” - Add Yours
May 6th, 2009 at 8:43 pm
I’ve been using this method for all my sharpening since I discovered it. I like to crank the Radius up to 250px sometimes for a grungy high contrast look.
May 6th, 2009 at 9:49 pm
Another advantage to high pass sharpening is the ability to selectively sharpen certain areas of the image using layer masks. For example, if you wanted to bring more attention to the eyes in a portrait without exaggerating imperfections in the skin, you could selectively sharpen just the eyes. High pass sharpening is a very powerful and highly customizable technique and it’s good to see it getting a little more attention. Thanks Darren.
May 6th, 2009 at 10:36 pm
There’s more to this sharpening technique… Let’s say there’s parts of the photo you “don’t” want sharpened… like someone’s skin in a portrait. You can actually erase some of the sharpening by opening the color pallet and setting it to 50% gray. Then just use the paint brush in any area on the high pass layer that you don’t want sharpened.
May 6th, 2009 at 10:59 pm
Somehow i believe u can achieve similar result as this high pass filter with the clarity slider in lightroom. just use the slider to +100 or somewhere along there. Correct me if i’m wrong tho :)
May 6th, 2009 at 11:27 pm
I have been using this method as well and find it to be the most effective. I didn’t know about the smart filters part – that will be useful for the future.
May 6th, 2009 at 11:42 pm
Excellent tip. Thanks for the article.
May 7th, 2009 at 12:04 am
I’ve been using this method for years. Be sure to look at sections of the image at 100% as it can be easy to over sharpen. I find often a radius of .5 or 1 is enough.
May 7th, 2009 at 3:01 am
I have also been taught to sharpen heavily at first so that you can see the effect clearly and then use the opacity slider on the sharpening layer to attenuate it to a reasonable level.
May 7th, 2009 at 4:32 am
I’ve used this method for a long time as well. I usually use a radius of 5 for my high-res images ( a lower number for smaller res) with soft light blending. I occasionally use overlay if I need a tad more sharpening.
May 7th, 2009 at 5:52 am
Thanks for the tutorial- i’ve been wanting to learn how to use the high pass ever since my friend told me about it…
May 7th, 2009 at 5:56 am
I use the high pass filter for sharpening sometimes, because sometimes I prefer the way it looks to the unsharp mask.
I am confused here though. It seems you are saying that one can’t run the unsharp filter on a new layer or that one can’t erase or selectively sharpen with the unsharp filter? I use the unsharp filter to selectively sharpen all the time. I’m not sure what you’re saying.
May 7th, 2009 at 10:59 am
You start with a fundamentally inaccurate statement: “The Unsharp mask has historically been the sharpening tool that most Photoshop users start out using. There are, however, different and better tools to use and one of these is the High Pass filter. One reason for this is that the Unsharp mask operates on the actual image pixels and it makes changes to those pixels.”
In CS4 the best way to apply sharpening – USM or smart sharpening – is generally to do it in a smart layer. This does NOT “operate on the image pixels” (if by that you mean “rewrite the underlying image data”). Sharpening applied this way is completely undoable and/or modifiable at a later date.
Not destructive sharpening methods can also be constrained to edges by several means. One excellent option in certain situations is to apply ACR’s sharpening – it is extremely powerful and lets you very easily constrain sharpening to edges. I do not always use this, but in certain images (for example those in which I want edge sharpening but want to avoid sharpening noise in uniform areas) it is a great technique. And it is also reversible and/or adjustable later on if you make sure to move the image to CS4 as a smart object.
In almost all situations this is a far better way to sharpen that applying the old “hard sharpening” that alters image data – and it is much easier than some of the workarounds that used to be necessary in older versions of Photoshop. Those methods are, in many cases, now anachronisms.
While this is almost always the best approach, there are more complex situations in which the use of masks and more exotic sharpening techniques can still pay off.
Dan
May 7th, 2009 at 1:54 pm
Thanks so much for this, I had never heard of it and I just tried it and I like it a lot better than the traditional sharpening method! It looks a lot more high quality!
May 8th, 2009 at 5:05 am
Great post. I really found this method of Sharpening very useful, and very good… I was wondering what could be the best way to do the sharpening.. Now you’ve shown it to me… Thanks!
May 8th, 2009 at 10:12 am
Great article – thank you. Appears to give a more controlled approach to sharpening and I likme the additional tip from Dean above to only sharpen parts of your image.
May 9th, 2009 at 7:13 am
As stated in the article, the reason this is so useful is for those of us on ancient versions of photoshop, USM, Smart Sharpening, or ACR are not available.
High Pass Filter is available to just about everyone with any version of photoshop, barring they have some of the original early 90s versions.
May 9th, 2009 at 9:51 am
Thank you very much for this information. I didn’t know there is this way of sharpening
May 9th, 2009 at 12:44 pm
I have been teaching this method of sharpening in my classes for a while now. Just as it says, you often get great effect in just sharpening around the edges. With a layer mask, you can then erase the parts of the image that you don’t want to sharpen, and again, like all of the best features of photoshop, it’s non-destructive.
Thanks, I’m going to point my students to this page to ensure they have a clear and concise explanation of how it’s done.
May 12th, 2009 at 7:01 pm
Excellent tutorial. I’ve mostly been using Smart Sharpen on CS4 but this is way better and I see better results. here is an example of a shot where I used the High Pass filter for sharpening
[http://www.flickr.com/photos/servo101/3517678861/]
As you can see, the edges on the dog’s fur are very well defined.
May 12th, 2009 at 7:01 pm
Sorry, mistake in link…they should really allow edits to comments…
http://www.flickr.com/photos/servo101/3517678861/
May 13th, 2009 at 11:44 pm
Great tutorial for more details we have a similar version
http://www.mutinydesign.co.uk/web-design-resources/sharpening-photographs-in-photoshop-using-the-high-pass-filter
May 22nd, 2009 at 2:51 am
This is a great technique. I’ve been using it a lot lately (almost too much but I’m playing and getting comfortable with the technique). The only thing I’ve found is that it hasn’t been useful when I only want to sharpen a portion of a shot — the eyes of a subject for example. But for an entire image it works just great.
July 31st, 2009 at 4:28 pm
thanks for the tutorial.. me too have been wondering how to use the high pass filter for sharpening purposes.. it’s been a great help! have a nice day!
August 8th, 2009 at 8:43 pm
Thanks for the tutorial, I love this technique, it’s works a lot better than the traditional sharpening tool.
August 14th, 2009 at 9:18 pm
A useful addition to this technique, courtesy of Martin Evening and Jeff Schewe is to use the Blend IF sliders in the sharpening layer if you want to only sharpen the mid-tones. For instance, set the Blend IF to sliders to split at about 75-125 and 165-210 (aproximate values).
This technique is discussed in their book entitled Adobe CS4: The Ultimate Workshop( 2009)
September 24th, 2009 at 6:29 am
When I use this technique I always use the blend mode “Linear light” and that’s the way I’ve been taught. I don’t know how different it is but I’m really pleased with the results.
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