For 64 bit Windows there is an installer provided containing GroIMP together with needed libraries. Just download GroIMP-*-win64.exe and run it (https://sourceforge.net/projects/groimp/files). The installer will ask you where to install and then copy all files to this location. It creates an icon in the start menu and also provides uninstall information.
For MacOS, there is also a package containing GroIMP and needed libraries
Just download GroIMP-*-MacOS.zip> and unzip to the location you want GroIMP to be installed, (https://sourceforge.net/projects/groimp/files).
Linux and others
For Debian and Ubuntu based systems, we provide an installer (GroIMP-*all.deb). For all other systems, just download GroIMP-*.zip and unzip it to the location you want GroIMP to be installed, (https://sourceforge.net/projects/groimp/files).
Adjusting the amount of memory available to GroIMP
For the Oracle JVM (formerly Sun JVM) there is a command line switch –Xmx to select the amount of memory that can be used by the Java application. For instance if you would want to start GroIMP with 3.5GB of memory, you could call:
java -Xmx1500m -jar core.jar
Note that on 32bit systems this is approximately the maximum you could get, even if your computer has more memory installed. This is because of virtual address space which limits the maximum to 2GB. On a 64bit system, no such limit applies and the memory could be set much higher. However, do not set the amount of memory higher than the memory your computer has physically installed, but instead to maybe 90% of the physically installed memory.
Note that the Windows installer creates an icon that calls GroIMP with the –Xmx option and an estimated size of memory depending on the physically installed memory, so in general, Windows users do not have to worry. However, for some larger models, increasing the default amount of memory to be used by GroIMP is advisable or to change the default settings, just do a right click on the menu item and go to the preferences and adjust the the call statement.
GroIMP needs the following Java environment on your system:
Java 2 JRE, Version 1.6 or later
GroIMP requires the installation of a Java run-time environment of version 1.6 or later. This can be obtained from Oracle.