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 1.7, released on 9 April 2021.


Installing Java


First, verify that you have Java installed on your computer.  For Windows, type “powershell”

(without the double quotes) within the “search” window just to the right of the “Start” icon, and then type

the “enter” key.  For a Macintosh, open the Terminal application, which is located in /Applications/Utilities/.

Double-click the Terminal application icon. 


Within your terminal window, type “java -version” (without the double quotes) followed by the “enter”

or the “return” key.  Java should output 3 lines of text into the window.  The first two should indicate

Java version 1.8.  The third line should include the words “64-bit server”.  If it does not say 64-bit,

then you have a 32-bit Java installed.  For Hoku to run properly, you will need to upgrade Java to the

64-bit version.  If you do not see those three lines, but instead you get an error message that java

cannot be found, then you will need to install Java (the 64-bit version).  Also, if you have version of Java

that is earlier than 1.8, then you will need to upgrade Java.


To install/upgrade Java, go to http://www.java.com/en/download/.  The website will determine which computer

your have and will point you to the proper download for your operating system, i.e Windows or macOS.

If you are given a choice, make sure to download the 64-bit version.  Now, you are ready to install Hoku.


Installing Hoku


The Hoku.jar file should be started from a terminal window, either Powershell in Windows,

or Terminal in macOS.  Installation instructions are directly below the following links.


<-- Click the icon to download the Hoku.jar file.

      Right-click and choose “Save Link As…” to download the file.


<-- Click the icon to view the Hoku icon.

      Right-click and choose “Save Link As…” to download the icon.


<-- For the Mac, click the icon to open the command file.

      Right-click and choose “Save Link As…” to download the file.



For Windows, download the Hoku.jar file, the Hoku icon, and

follow these instructions for Windows to install Hoku.


For Macintosh, download all three files above, and

follow these instructions for Macintosh to install Hoku.



Upgrading your Hoku version


To upgrade Hoku, when a new version is released, download Hoku.jar, and

overwrite the previous version of Hoku.jar.





A series of introductory videos are 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.)




When you first start Hoku, a built-in Tutorial is displayed.

You may bring up the Tutorial within Hoku at any time.

From the “Hoku” pull-down menu, select “Tutorial” to revist.


       For advance work with “flowcharts”,

 <-- click this icon to download the PDF file.







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  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


                                                  12 February 2021


Updated: 16 April 2021