README
======

GIMP 3 VERSION
--------------

This fork carries the port of the wavelet sharpen plugin to GIMP 3. The
original plugin by Marco Rossini is at
https://github.com/mrossini-ethz/gimp-wavelet-sharpen and supports GIMP 2.x.
The port is being offered upstream; until it is merged, this is where it lives.

What is new in the GIMP 3 version (see ChangeLog for details):

- Runs in GIMP 3.0 and newer.
- 16-bit and floating point images are sharpened at full precision.
- Scripts use the same arguments as before, and GIMP remembers the last used
  settings.
- Builds with current compilers again, and a few bug fixes.

For building and installing see the file INSTALL. Please report problems with
the GIMP 3 version at
https://github.com/sandbranch/gimp-wavelet-sharpen/issues

The wavelet sharpen plugin increases apparent sharpness of an image. The amount
of unsharpness in the original image can be taken into account. The plugin is
not compareable to the builtin 'Sharpen' filter of the GIMP, however the
results are simmilar to the ones with the builtin 'Unsharp mask' filter.

LICENCE
-------

Copyright (C) 2008 by Marco Rossini. Distributed under the General Public
License GPLv2+. See the file COPYING which contains the license.

The plugin works in GIMP 3.0 and newer, on RGB and grayscale images of any
precision (8 and 16 bit integer as well as floating point). The alpha channel
is never sharpened.

INSTALLATION
------------

See the file INSTALL for instructions how to install the plugins.

USAGE
-----

There are two circumstances that makes it necessary to use the sharpen filter:

1. To reduce the effects due to aliasing of an picture which is in focus.

   a) Set the amount of sharpening using the slider.

   b) You may want to have the checkbox 'Sharpen luminance only' activated in
      order to avoid having colour artifacts (especially in noisy images).

   c) The sharpening radius can be left at 0.5.

2. To sharpen a picture which is out of focus.

   a) Set the amount of sharpening rather high (at first).

   b) Adjust the sharpening radius using the slider to choose the frequency
      part in the image which is to be increased in contrast. This means for
      blurred pictures you may want to set the value high (which sharpens slow-
      ly varying image features, leaving high frequency noise alone). Use low
      values if the image has many details.

   c) Set the sharpening amount back to a value that pleases your eye.

   d) You may want to have the checkbox 'Sharpen luminance only' activated in
      order to avoid having colour artifacts (especially in noisy images).

SCRIPTING
---------

The plugin can be called from scripts as "plug-in-wavelet-sharpen" with the
arguments "amount" (0 to 10), "radius" (0 to 2) and "luminance" (sharpen the
luminance only), the same as in the GIMP 2 version.