Photo Post Processing Notes: 1 - Capture NX High Pass

Posted: Mon Sep 01, 2008 4:02 pm

Decided to try something new as I have never felt very proficient at Post Processing. I think I will focus on a single tool for each series, and provide the following:

What I use
Why I use it in a particular photo
Possible alternatives
Images and screenshots to "see" the tool.
Followed by discussion; to explore the technique, expand on overall knowledge of the tool, and possibly locate errors in my own workflow.

Photo PP Notes: 1 - High Pass

At times I use the high pass tool in NX, Here is an example of a photo that I used it within.

I found that the High Pass allows me to get a little extra pop, adding some apparent depth to a photo, or selective portions within a photo while also sharpening it.

Selecting the High Pass filter, a popup box appears, adjusting the slider increases/decreases the pixel radius. As the pixel radius increases the image will turn from all grey, to an increasing display of edges/lines with color. Overdoing it will lead to color bleed outside the normal boundaries. It is easy to fix by decreasing the pixel radius at anytime. I have found by experimenting that some excellent results can be stumbled upon Smile

The next step is to perform an opacity adjustment. I experiment with the blending modes but often prefer "Overlay" or "Multiply".

*Note, overlay tends to concentrate the filter creating a "lighter" image focussing on the luminosity channel. While Multiply tends to concentrate the filter creating a "darker" image. Both can have pleasing results.

Before:

After:

I understand it is hard to see, however what I "feel" it does is takes the lines and shapes and locates the edges in color, and amplifies them. It is somewhat like selective sharpening but I find that in most instances it does not have a tendency to amplify noise present in the image. Possibly even like a local contrast of sorts.

Now as I said I am no photo editing genius, so here is why I posted this. In the hopes that individuals will expand upon it, possibly provide better description of what High Pass filtration does and what its correct uses are, as well as what some incorrect uses might be. I would appreciate some insight and a chance to learn something new as well Smile