High Pass or Unsharp Mask?

[domenico Foschi]

A friend of mine who has been tutoring me in Photoshop, regards the high pass filter superior to unsharp mask.
Does anybody have an opinion?
Best regards.

[Steve J Murray]

High Pass seems to have a rather large effect on the image. I wonder if your friend is using it as part of a "selection" process in a layer. There are many PS actions available that select edge areas for sharpening and the smooth areas are left alone.

This site has many links to information about sharpening techniques:

http://www.canonians.com/sharpening.htm

[paulr]

Well, I'd have to know the context to really understand what he means. Personally, I use unsharp mask exclusively, but to take advantage of its power, I use it in ways that are a bit more involved than just plugging in values and hitting go.

A great resource is Real World Photoshop CS, by David Blatner and Bruce Fraser. It has a whole chapter on sharpening. It goes into details on how to use a sharpening layer with unsharp mask, and how to use this tool to focus your sharpening on the midtones so you don't blast any pixels to white or black. This technique also allows you to to use luminosity mode, so you don't cause color fringing in a color image (similar to sharpening the L channel in LAB mode, but doesn't require a color mode change). The book also talks about sharpening through an edge mask with USM, so you increase edge contrast without increasing grain or noise. You can then use the same mask to blur areas that aren't made up of edges, to actually reduce grain and noise, without hurting sharpness.

Lots of other techniques, including high pass sharpening. The authors of the book advocate sharpening during three different phases of the workflow, and say they often use high pass sharpening for the final sharpening before output. I don't know why they like this technique when they like ... the book isn't completely clear on this point.

[Will Strain]

They are different tools - some images react better to one method than another.

In truth I use at least three sharpening methods, and in any given image, I'll usually use two. A general USM to get a scan up to something useful, then a highpass sharpening layer to finish before printing.

But I don't have a formula. It depends too much on the individual image.

[John Brewer]

USM is the only one of the Photoshop sharpen filters thats of real use with photographs IMHO. By filter I mean filter in the drop down menu. Much more advanced sharpening can be achieved using for example the high pass filter, sharpening different channels etc. It's a case of 'horses for courses' really. I digitally restore photos and I recomend looking at at 'Photoshop Restoration and Retouching' by Katrin Eismann.

J

[Alan Davenport]

I'll muddy the water a bit with my sharpening routine. I use high pass sharpening immediately after scanning, not too much but just to crisp up the edges a wee bit. After everything else is done and the image is flattened and ready to save as a TIFF for printing, I use JB's Smart Sharpen filter to tailor the unsharp mask to the areas that need it most. It often takes me a couple of trys to get the result I'm after in the last step.

[Doug Dolde]

I bought Pixel Genius' PK Sharpener. Has a very large bag of tricks, including output sharpening for various media. Highly recommended.

http://www.pixelgenius.com/sharpener/info.html

[Ben Hopson]

More often than not I use the High Pass filter for sharpening. Try creating a duplicate layer, run the High Pass filter then switch to Soft or Hard Light Blend Mode. I usually prefer Soft Light, but each has it's place. If the effect seems too strong reduce layer opacity. Sometimes I use a combination of High Pass and Unsharp Mask to reach a desired effect.

[paulr]

To those who use high pass sharpening a lot, how would you describe the differences between what you can achieve with it vs. unsharp mask (including using USM on a sharpening, layer, etc.)?