Digital Earth Watch (DEW) software and SalsaJ software (for Hands-On Universe) are image analysis applications and key parts of the Global Systems Science curriculum. DEW software is free from this site.  SalsaJ software is also free and can be downloaded from the Global HOU project.

Digital Earth Watch (DEW)

Digital Earth Watch (DEW) software includes 4 software programs:

  • ColorBasics
  • DigitalImageBasics
  • AnalyzingDigitalImages (which, as of Nov 2011, includes ForestAnalysis and VegetationAnalysis)
  • MovieTracker

A complete set of satellite images accompanies the DEW software for use in exercises.

There is also a student book, ABC's of Digital Earth Watch Software and a Teacher Guide aimed at helping students learn to analyze Earth images qualitatively and quantitatively for changes in ecosystems over time, including effects of urban growth, fires, volcanic eruptions, etc. , and the software tools can be used with ANY jpeg image files, so students would be able to do their own investigations after learning the basic principles.

DEW software is available free: GSS Software Download page.

DEW Software descriptions:

ColorBasics has tools for understanding:

  • the difference between color as pigment and color as light
  • how colors are created in a computer display
  • color spaces

DigitalImageBasics has tools for understanding:

  • the relationship between pixels and resolution
  • how camera colors are displayed on a computer screen
  • tools for analyzing color in images
  • the meaning of “false color” and
    representation of invisible wavelengths as visible colors.

AnalyzingDigitalImages has tools for:

  • enhancing and measuring color in images
  • measuring spatial elements in images
  • making color masks
  • analyzing time series of images

MovieTracker has tools similar to AnalyzingDigitalImages, but applied to movies instead of still images.

SalsaJ Software (For Astronomical Image Analysis)

SalsaJ is software for Hands-On Universe (HOU) students to display, analyze, and explore real astronomical images and other data in the same way that professional astronomers do, making the same kind of discoveries that lead to true excitement about science. It is used for activities and investigations in the GSS books A Changing Cosmos and Solar System Science. A Teacher Guide can be downloaded from the GSS Download Site. European HOU (Eu-HOU) has number of other exercises, complete with data to download and detailed instructions for use. The flexibility of the SalsaJ tool enables students and teachers to extend the exercises with their own observations.  This software replaced the HOU-IP 2.0 software. 

SalsaJ is available for download free of charge from the HOU software page at

Hands-On Universe Image Processing Software (HOU-IP 2.0)

[GSS and US-HOU no longer support HOU-IP 2.0. However, it is still possible to download, install, and use the software for 30 days, after which registration code is needed. A registration code can be provided free by HOU staff.]