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 2.0, released on 17 March 2024.


New Features in version 2.0


The major change is that Hoku is now implemented as an application that has the necessary Java runtime code

embedded inside.  As a result, there are different downloads for different computer platforms,

and Java does not need to be installed separately.


Also, four new modules were added, Align, Imfill, Insert, and SID.  Align displays two images,

an anchor image and an image to be stretched by the user to fit the anchor.  Imfill will reduce

extreme values, within specified regions, to prevent veils in Normalize. Insert will put one image

into another.  SID implements the Spectral Information Divergence algorithm.
See the Release Notes from the Hoku pulldown menu for the complete list of changes.


Installing Hoku – as System Administrator


To install the new Hoku application, you must have system administrator privileges on your computer.

If you do not have such privileges, see if a system administrator will load the software for you.

If neither is possible, then see the next section on how to install a version of Hoku without system administrator privileges.


Hoku applications are available for the macOS, Windows, and Linux. Download the Zip file containing

the appropriate installation program from the following links. Double-click the downloaded Zip file

to extract and decompress the installation folder.





Computer Platform



Macintosh, ARM, M-chips



Macintosh, Intel Processors






Linux, Ubuntu, Intel Processor



Linux, Ubuntu, ARM, M-chips



Full instructions on how to install Hoku are contained in the “Instructions” file within each folder.


Installing Java on your computer is not needed for these applications.

They have the necessary Java runtime code embedded within them.



Installing Hoku – without System Administrator Privileges


To run the InstallHoku.jar program, and to run Hoku itself, you will need to have Java software

installed on your computer. See the Installing Java section below on where to find and install Java.


Next, download  ->  InstallHoku.jar


The best way to run InstallHoku.jar is to bring up a terminal window. In Windows, that is

a command prompt. In macOS, that is Terminal.app that you find in /Applications. In Linux,

that a Terminal window. Now, change to the directory where you put InstallHoku.jar

when you downloaded it. That might be the Desktop or it might be Downloads.

For the Desktop, that command would be:


             cd Desktop


Given that you have already installed Java, you can run InstallHoku.jar with the command:


             java -jar InstallHoku.jar


This installation program will determine which type of computer you are using,

either Windows, macOS, or Linux, and install the appropriate routines.  Follow

the instructions in the program.   You may delete InstallHoku.jar when it finishes.


InstallHoku.jar will install a folder, named HokuUtilities, in your home directory.

Do not delete that folder or modify anything within it. The install program will put

an icon shortcut on your computer Desktop which can be used to start Hoku.


Upgrading your Hoku version


In the future, to upgrade Hoku, when a new version is released, download the new installation program

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 of Hoku requires at least Java version 17.

We recommend that you download Java 21 from:  



Select the “JDK 21” tab, then either the “Mac”, “Windows”, or “Linux” tab.  This upgrade beyond Java 1.8 was necessary,

because Java version 8 does not have a version that runs native code on the new Apple M1/2/3 hardware chips.

Version 21 is a long-term, stable version that has a native code for the Apple M1/2/3 chips.  On Windows,

just download the Windows version of Java 21, and for Linux on a computer with Intel processors,

download the Linux_x64 version.  For Linux on a Mac with Apple silicon (M-chips), download Linux_arm64.

For the Mac, determine if you have the M1/2/3 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.




A series of introductory videos will be made available shortly:





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, 2023,2024  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


                                                  17 March 2024


Updated: 17 March 2024