DIY High Pass Filter (and my soul patch!)

[wulf]

This shot started with looking for more information about high pass filtering. Somehow I drifted from that to envisaging a headshot using a paintbrush to give me an enhanced soul patch (and thus also another shot for my fiftytwo project).

I found some useful articles online. For example, there was one about creating a sketch effect with The Gimp which gave an illustrated explanation of what high pass filtering is about. I adapted the method and ended up with a different series of steps but first, let me show you the before image:



After cropping for a tighter composition, I created a couple of duplicate layers. On the top most one, I applied a gaussian blur (20px but it will depend on the image). This is a low pass filter. It keeps the broad areas of colour but obscures all the details. Isn't that the opposite of what I wanted? Yes, but by setting the top layer to "grain extract" mode the result changes dramatically. Areas that are soft in the original picture become grey but those which have reasonably sharp detail (and thus are quite different to the blurred copy) become revealed. I merged the two duplicate layers together and used the curves tool to further emphasise the details.

Time for more layer modes magic. I set the combined layer to overlay mode and suddenly the original photograph was revealed but with the details noticeably sharper than before. The result can be fine tuned by adjusting the opacity of the overlay layer. You can also create one or more duplicates of that layer to increase the effect or apply a layer mask to apply it to some areas and not to others. I decided that it overemphasised the skin pores on my forehead so applied a graduated mask but the best choice depends on the picture. Here is the end result:



Is that better? It is definitely sharper and makes for a more striking image. What is more, while describing the process takes a lot of words the steps could easily be applied in a few seconds. Therefore, this is a better approach than the selective sharpening I described earlier this year.

If you have a play with the technique, then please feel free to post your results here (before and after shots and discussion of tweaks you make to the process particularly welcomed).

Wulf

ps. For reference see the Gimp guide on layer modes.

[lacealou81]

from what I understand...high pass really does an awesome job of bringing out highlights, tho I'm so new, I'm still just learning! great job on bringing out those details, tho.

[pkd14u]

Oh cool! I just love trying new techniques with Photoshop. I had to guess on a few things, like what is "grain extraction" mode? Oh well, I used "despeckle" on that layer. Not sure it did anything, but hmm.

Here is one of my results, before and after.

Before. Used my usual sharpening technique.


After. Using the High Pass technique described above. I really like this. I put the overlay to about 30%.


This one is using a combination of Wulf's technique and the other techniques linked on the "Urban Decay" thread.


I think I like the third one best. The differences are pretty subtle.

Thanks for the tutorial Wulf!

pkd14u

[krypticide]

To be honest, I don't really see much difference between the before and after shots shown here, except for some contrast maybe. I'd ask what I'm supposed to be looking for, but that sort of defeats the purpose...

[wulf]

Originally Posted by krypticide

To be honest, I don't really see much difference between the before and after shots shown here, except for some contrast maybe. I'd ask what I'm supposed to be looking for, but that sort of defeats the purpose...

Generally, the best sharpening is meant to be quite subtle. If you compare pkd's three pictures (I open them up in tabs in Firefox and switch between them) you will see, for example, that the high pass technique avoids strange blobs showing up in the reflection on the glasses (for contrast, it would be interesting to see the original, too).

My two shots are harder to compare (due to the cropping) but note how the hairs (beard and paintbrush) bristle more but without the picture looking obviously sharpened.

You can of course make the effect more dramatic - stack up two or three overlay layers and it becomes much more pronounced.

Wulf

[ditch_azeroth]

soul patch - that's original. lol. nice post process. wouldn't change a thing. anybody tell you have a semblance to jack black?

[wulf]

Yep - I have had that before but there are some big differences between me and Jack... like he's famous and I'm not

Wulf

[wulf]

Here is another pair of shots processed in a similar fashion. This pair is easier to compare because they are the same size.

Before



After



Wulf

[Alex168]

I see what you done, but i m going to comment!

This seems to render some quite intresting results, you get a relativly good sharpening. I honestly hate sharping my images why? because i just dont know how to, i do know where the tools are and whot not but i just dont like the results that i get from using the unsharped mask.

Now this seems to be quite the nice alternative for sharpening an image.

Wulf have you tried this on other images but portraits? Would be intresting to see the results then.

About the last image you posted, i quite like the final product but i dont like it that you decided to "sharpen" the whole image so to speak, i quite liked the bokeh on the first image and this was a bit removed by the sharpening..

thanks for the tip Wulf

[i_luv_ph0tos]

How do you do that on Gimp??