The Remap Alpha tool lets you remap the alpha using a single curve manipulation interface similar to Blend Curves. The curve defaults to the identity mapping.

An invert button provides inversion of the alpha after the curve mapping. This tool affects alpha only; the RGB channels, if present, are passed through unchanged. The pixel format of the output is the same as the pixel format of the image input. If the image has no alpha, then the output will have an alpha channel, properly modified by the curve remapping.

For more detailed curve manipulation, control points can be added to, or deleted from the curve.

To add a control point to the curve:

1. With the cursor in the curve window, press + (plus sign) to enter a mode where each click on the curve creates a control vertex at that location.

To delete a control point from the curve:

1. With the cursor in the curve window, press - to enter a mode where each click on a control vertex deletes the control vertex at that location.

To exit the Add or Delete control point mode:

1. Press Esc.

The Remap Alpha tool has the following parameters: