Benefits
of the plugin

Transparent background or foreground color
Make any brightness range transparent
Fade-out the transparency.
Use for graphics, gifs etc.
Use for correction layers

The transparency filter plugin works with these image modes (Windows and Mac)...
8 & 16 bit / channel: RGB.

Transparency
filter controls

This is the transparency plug-ins control panel (Windows). Click to enlarge. The controlpanel and preview area can be changed by dragging the sides.

The filter has these sets of controls:

1. Transparency area
2. Transparency in brightness range
3. Transparency in fore- or background.

Example -

The transparency plugin is a powerful filter for making transparent backgrounds as well as making any other limited color, area or brightness range transparent. Here we made the blue sky transparent.

The Make transparent control-group

Make transparent

This control set determines which brightness areas should be made transparent.

Lights - Make white fully transparent end diminish transparency towards black.
Darks - the reverse of above.
Within limits and Outside limits - the limits are set by the next control set.

Brightness range

Brightness range

If you select within limits or outside limits, this control panel will become active.

If you select within limits, only pixels brighter than dark limit and darker than light limit will be changed.

If you select outside limits, only colors darker than dark limit and brighter than light limit will be changed.

Target is only functional if softness is set higher than 0. Target sets which brightness value is to be changed the most. Depending on the setting of softness, brightness values brighter or darker than the target will be changed in lesser degrees.

Softness

This is an excellent tool for retouching lights, mid tones or darks. If you place a monochrome layer underneath, you can tone the lights or darks with that.

Transparent mask

This lets you target two colors for transparency: The foreground color and background color selected in the host application.

In addition you can either enable or disable all the above controls for targeting a brightness range.

Spread selection

If you set spread selection to 0, only the exact color will be made transparent. As you raise the slider, more and more neighboring colors will be included.

Example - Creating a HDR image out of two images

Here's the regular shoot of a difficult situation.

The lights are overexposed and the paintings are underexposed

We want to combine the best of these two image

Place the dark image as a layer on top of the lighter image.

Invoke the plug-in on the darker layer and make the darks transparent.

This is what you should end up with: