There are two versions of the HiRISE Toolkit for ENVI found in the
following subfolders:

   ENVI_4.6_or_Older/ : Toolkit for ENVI 4.3, 4.4, 4.5, and 4.6.

   ENVI_4.7_or_Newer/ : Toolkit for ENVI 4.7 or newer.

To install the toolkit, simply navigate into the appropriate subfolder
and follow the instructions delineated in the "INSTALL.txt" file.

Release Notes:
--------------
As of v.4.7 (2009) the ENVI software uses a new projection engine. This
new projection engine aligns with the ArcGIS software suite and provides
enhanced support for geographic coordinate systems, map projections,
datums, and ellipsoids. Consequently, the HiRISE Toolkit for ENVI was
updated to take advantage of the new functionality, and previous users
of the toolkit may notice changes in the naming convention of certain
map components. All of the geographic systems, conversions, and constants
are exactly the same as in previous versions of ENVI & the HiRISE Toolkit
with the following changes in naming:

Projection: "Equirectangular"     --> "Equidistant_Cylindrical"
Projection: "Polar Stereographic" --> "Stereographic (ellipsoid)"
Datum:      "Mars 2001"           --> "D_Mars_2000" or "D_Sphere_Mars"
Ellipsoid:  "Mars 2001"           --> "Mars_2000_IAU_IAG"