Hoku is a Java-based software package to process multispectral image data sets

to recover writings that have been damaged or erased.  It is distributed free-of-charge,

without warranty.  The current version is 1.9.5, released on 29 September 2023.


Installing Hoku


Download the InstallHoku.jar file to your computer’s Desktop.

The Hoku software no longer runs on Java version 8.

To run InstallHoku.jar and Hoku itself, we recommend Java version 20.

See Installing Java below for how to install Java 20.


<-- Select to download InstallHoku.jar.




Double-click on the downloaded InstallHoku.jar file.  The installation program

 will determine which type of computer you are using,  either Windows or macOS,

and install the appropriate routines.  Follow the instructions in the program. 

You may delete the InstallHoku.jar file when it finishes.


New Features in version 1.9.5


Three new modules were added, ICA, MNF, and Watermark.  ICA implements Independent
Components Analysis.  This is similar to PCA, but instead it separates the image on a statistical basis.
MNF implements Maximum Noise Fraction from the remote sensing world.  ENVI refers to this
as Minimum Noise Fraction.  The third module, Watermark, invisibly inserts a watermark image, provided
by the user, into an 8-bit output image.  The watermark can be extracted with the same module.
Several other slight modifications were made.  See the Release Notes from the Hoku pulldown menu.


Upgrading your Hoku version


In the future, to upgrade Hoku, when a new version is released, download the new InstallHoku.jar,
and double-click to install the new version.  Your existing data, on your Hoku Shelf and Hoku Desktop
will not be changed.  All of your existing data will be available to you in the new version of Hoku.


Installing Java


Previous versions of Hoku ran on Java version 8 (1.8).  This latest version requires at least Java version 17.
We recommend that you download Java 20 from:  https://www.oracle.com/java/technologies/downloads/.
Select the “JDK 20” tab, then either the “Mac” or “Windows” tab.  This change was necessary,
because Java version 8 does not have a version that runs native code on the new Apple M1/2 hardware chips.
Version 20 is a long-term, stable version that has a native code for the Apple M1/2 chips.  On Windows,
just download the Windows version of Java 20.  For the Mac, determine if you have the M1/2 chips from your computer,
then download either the “ARM64” version of the code, or the “x64” version of the code if you have an Intel Mac.




Although they were created for an early version of Hoku, a series of introductory videos is available:


Multispectral Image Processing (37 min.)

Getting Started – Macintosh (14 min.)

Getting Started – Windows (14 min.)

Creating a Job on Hoku (36 min.)

Extended Features of Hoku (1 hr. 5 min.)

Background Suppression (35 min.)




You may contact the author at the email address below if you have questions,

need help on a specific problem, run into problems, or have comments or suggestions.




    Copyright (C) 2021, 2022, 2023  Keith T. Knox


    This program is free software; you can redistribute it and/or modify

    it under the terms of the GNU General Public License as published by

    the Free Software Foundation; version 2 of the License.


    This program is distributed in the hope that it will be useful,

    but WITHOUT ANY WARRANTY; without even the implied warranty of


    GNU General Public License for more details.


    You can read the GNU General Public License in LICENSE.txt.

    You may also obtain a copy of the license by writing to the

    Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,

    Boston, MA 02110-1301 USA.


                                                  Keith Knox


                                                  29 September 2023


Updated: 29 September 2023