Dynamic Masking with Threshold and Levels

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Publication Date: 28-Dec-21

Duration: 7:09

The principle is as follows:

Duplicate the image three times (start with Merge Visible if needed)

Top image:

Add first Threshold and then Levels in child (masking) position.
Set blend mode Erase.
Blend Ranges, left graph, pull down left node.

Group top two image layers.

Turn off (hide) bottom image and Levels.

Adjust Threshold to give coarse selection.

Blend Ranges as above gives selection upward from blacks.
To select from whites, change Blend Ranges on top image to have left graph, left node up, right node down.

This gives a hard-edged selection. If you want feathering, you can use a blur and masking, though this can be tricky. Easier is to use the method as in the next step.

Note the Threshold percentage value, turn off layer and turn on Levels.

Set Black and White Levels sliders to either side of the Threshold percentage value.
The gap between the Black and White sliders will determine the feathering.

You can also dispense with the Levels adjustment and go straight to Levels.

With Levels, you can leave Black at 0 and adjust White, or leave White at 100% and adjust Black. Try it!

Add appropriate adjustment (eg Curve, Selective Colour), blending and masking to top Group.

Turn on bottom image layer to see the final image.

You can also turn it on for previous step when adding final adjustment to see overall effect.

Go back and adjust Threshold/Levels, Blend Ranges and Opacity as needed.

Note: You can also use Curves instead of Levels for further effects and a different control style.

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Dynamic Masking with Threshold and Levels

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