Today’s Question: As a part of my workflow in Lightroom, I hold down the Option key [Alt key on Windows] and move the masking slider to adjust the area in the image that I want to sharpen. Sometimes when I am doing this, I think that the result that I see would make an interesting abstract. I think this must be a little like the posterization effect in Photoshop, but when I try to use that approach, it doesn’t seem to produce the same outcome I get with the masking slider. What is it that is actually happening in Lightroom with the masking slider and how could I best reproduce that effect in either Lightroom or Photoshop?
Tim’s Quick Answer: The effect you’re seeing is somewhat similar to a result you can achieve with the Find Edges filter in Photoshop. The approach involves using the Find Edges filter and then creating additional contrast and possibly inverting the result.
More Detail: To get started, open the image in Photoshop. Then create a copy of the Background image layer. From the menu bar choose Filter > Stylize > Find Edges. There are no parameters for this filter, so you’ll simply see the result in the image.
Next, add a Hue/Saturation adjustment layer, and reduce the Saturation completely. This will remove the color created as part of the Find Edges filter, so that you have a black and white version of the image.
You can then add a Levels (or Curves) adjustment layer and drag the black and white point sliders inward to create extreme contrast for the photo. You will generally want to bring these end points very close to each other, possibly all the way until those end points are touching each other. Pay attention to the detail within the photo to help choose where those two end points should meet.
You can then add an Invert adjustment layer if you’d like to reverse the areas that appear black versus white, which will provide the same basic result you were seeing in Lightroom. You may also want to apply a slight blur to the Background Copy layer, using the Gaussian Blur filter.
Note that in some cases you may prefer the effect produced by first working with a lower-resolution image, and then increasing the size of that image to exaggerate the size of the lines created by the effect.
It is worth noting that you could also simply produce a screen capture of the effect directly from the Develop module in Lightroom when using the preview feature (by holding down the Alt/Option key on the keyboard) while adjusting the Masking setting for the sharpening effect. Because the image is abstract, having a relatively low-resolution screen capture won’t have a significant effect on the appearance of the final image.