ENVI 4.7 Tutorial
ENVI 4.7 Tutorial

What's New in ENVI 4.7

New Sensors

ENVI can read, display, and georeference COSMO-SkyMed radar data. You can also save COSMO-SkyMed metadata to XML format. See Working with COSMO-SkyMed Data for details.
ENVI and ENVI Zoom can read and display RapidEye Level-1B (Basic) and Level-3A (Ortho) data. Level-1B data often come with rational polynomial coefficients (RPCs), which you can use for orthorectification or DEM extraction. You can also use ENVI's Build RPCs tool to create RPCs from Level-1B data. Finally, you can use RapidEye data with Gram-Schmidt spectral sharpening and as input to the ENVI Atmospheric Correction Module. See "Opening RapidEye Files" in ENVI Help for details.
ENVI reads, displays, georeferences, and computes sea surface temperature (SST) for AVHRR data from the NOAA-19 satellite. See Computing Sea Surface Temperature for details on the equations and coefficients used for SSTs.

Enhanced Map Projection Support

ENVI and ENVI Zoom now use the ESRI® Projection Engine to greatly expand the range of available map projections. In addition to 30 standard map projections already supported, ENVI and ENVI Zoom will also read any projection type from a geodatabase or layer file. See the ArcGIS® Help for a full list of supported projections.
See Map Projections for details.

Improved Landsat Tools

ENVI and ENVI Zoom can read Landsat MSS, TM and ETM+ metadata files from the Global Land Cover Facility (GLCF) or from the U.S. Geological Survey (USGS). The metadata files provide information needed to open the associated GeoTIFF imagery. See Opening Landsat Files for details.
ENVI uses updated parameters and coefficients for computing spectral radiance and exoatmospheric reflectance in Landsat data. The Landsat Calibration Tool has been updated to retrieve calibration parameters from metadata files that accompany Landsat MSS, TM or ETM+ GeoTIFF imagery. See Landsat Calibration for details.

Print Layout View in ENVI Zoom

The new Print Layout view provides a powerful way to view, modify, print, and export maps. You can apply ESRI templates to ENVI Zoom image processing results and workflow results. You can export maps to .jpg, .gif, .pdf, .bmp, .tif, and a variety of other file types. You can now also send maps to a printer or plotter. This feature is only available on Windows 32-bit platforms with an ArcGIS Desktop license installed (ArcView®, ArcEditor™, or ArcInfo®). See "Working with the Print Layout View" in ENVI Zoom Help for details.

New Vector Tools in ENVI Zoom

ENVI Zoom has two new right-click menu options available when editing vector layers. Use the Smooth option to interactively smooth individual polygon vectors, using the Douglas-Peucker line simplification algorithm. Use the Rectangulate option to smooth polygon vectors so they are more rectangular in shape. This tool is especially useful for rooftops, buildings, fields, parking lots, etc. See "Smoothing Vectors" and "Rectangulating Polygons" in ENVI Zoom Help for details.

New Toolbox Category in ENVI Zoom

A Toolbox has been added as a new category to the category bar. In the Toolbox, you initiate image processing and, if you have ENVI EX, workflows. You can initiate a Toolbox function by double-clicking on it, or by dragging and dropping an item from the Layer Manager, the Data Manager, ArcCatalog, ArcMap, or the Windows files manager onto a Toolbox function. See "Toolbox" in ENVI Zoom Help for details.

Chip Display to PowerPoint in ENVI Zoom

This feature is only available on Windows 32-bit and 64-bit platforms with the PowerPoint presentation graphics program installed. ENVI Zoom can save a chipped image that appears in the Image window as a new slide to a new or existing PowerPoint presentation. See "Output Chip to PowerPoint" in ENVI Zoom Help for details.

Chip Display to the Print Layout View in ENVI Zoom

This feature is only available on Windows 32-bit platforms with ArcGIS Desktop (ArcView, ArcEditor, or ArcInfo) installed. ENVI Zoom can transfer a chipped image from the Image window to the Print Layout view. From there, it can be printed, exported to a variety of file types, and viewed in ESRI templates. See "Output Chip to the Print Layout View" for details.

Other Changes in ENVI 4.7

  • ENVI and ENVI Zoom take advantage of reduced resolution data sets (also called RSETs) generated by RemoteView software, to speed the display of imagery. These files are versions of the original image at various reduced resolutions. They are in NITF 2.1 uncompressed format, so you must have a NITF/NSIF Module license in order for ENVI to use them to display images. See Reduced Resolution Data Sets.
  • ENVI exports raster and vector results from several SPEAR workflows to a file-based geodatabase. The following workflows offer this capability: Anomaly Detection, Change Detection, Lines of Communication (LOC) - Roads and Water, Pan Sharpening, Relative Water Depth, and Watercraft Finder.
  • ENVI Zoom reads and displays the following file types: MrSID, ERDAS IMAGINE, SPOT DIMAP, ESRI layers, ESRI simple/standalone feature classes in a geodatabase, and ESRI GRID files.
  • In ENVI Zoom, Windows users can click and drag a file from ArcMap, ArcCatalog, or the Windows file manager (including search results) into the Image window.
  • ENVI Zoom supports ESRI layers and feature classes. ESRI layer support is only available on Windows 32-bit platforms with ArcGIS Desktop (ArcView, ArcEditor, or ArcInfo) installed.
  • ENVI Zoom includes spectral filter functions for the GeoEye-1 sensor for use with Pan Sharpening. ENVI Zoom will also read GeoEye-1 metadata files to determine which images to load and display.

New ENVI EX Workflows

Workflows have been added to ENVI EX for classification, image difference change detection, thematic change detection, and RPC orthorectification. Workflows guide you through the process of selecting files, setting parameters, and exporting results. The new workflows are:

Feature Extraction

The Feature Extraction workflow is included with ENVI EX and is no longer available as a separate add-on module for ENVI. With Feature Extraction, you can identify objects of interest from high-resolution panchromatic or multispectral imagery, classify the objects into known features using rule-based or supervised classification, and output the classification results to shapefiles.


The Classification workflow allows you to categorize pixels in an image into many classes. You can perform an unsupervised classification with no training data, or you can perform a supervised classification, where you provide training data and specify the classification method.

Image Difference Change Detection

The Image Difference workflow allows you to compare two images of the same area taken at different times and identify differences between them. The difference can be computed on a specified input band or on a feature index, and you can optionally apply thresholding.

Thematic Change Detection

The Thematic Change workflow allows you to take two classification images of the same area taken at different times and identify differences between them. The resulting classification image shows class transitions, for example, from urban to water.

RPC Orthorectification

The RPC Orthorectification workflow performs orthorectification of a single-scene image using the rational polynomial coefficients (RPC) model.

Hardware and Operating System Requirements

Hardware and Operating System Requirements

A network interface card (NIC or Ethernet) is required for software-based node-locked and floating licenses. The following table describes the supported platforms and operating systems for IDL, ENVI, ENVI Zoom, and ENVI EX.

Table 1-1: Hardware Requirements for IDL and ENVI





Supported Versions a



Intel/AMD x86 32-bit


XP SP2, Vista

Intel/AMD x86_64 64-bit



PowerPC 32-bit



Intel 32-bit

Intel 64-bit



SPARC 32-bit

Solaris c



SPARC 64-bit

Solaris c



Intel/AMD x86_64 64-bit

Solaris e



Intel/AMD x86 32-bit

Linux b, c

Kernel version 2.6.9
glibc version 2.3.4
gtk2 version 2.4.13


Intel/AMD x86_64 64-bit

Linux b, c, d

a Supported versions indicate that IDL, ENVI, ENVI Zoom, and ENVI EX were either built on (the lowest version listed) or tested on that version. You can install and run IDL, ENVI, ENVI Zoom, and ENVI EX on other versions that are binary compatible with those listed.
b The LINUX version of IDL is built on RedHat 4. If your version of Linux is compatible with the listed kernel and glibc versions, you should be able to install and run IDL, ENVI, ENVI Zoom, and ENVI EX.
c The IDL Workbench requires the GTK+ library version 2.4 or later. Printing functionality in the Workbench requires GTK+ library version 2.10 or later. If GTK+ version 2.4 or later is not available, IDL will only run in console mode.
d On 64-bit Linux systems, the IDL Workbench requires that your platform's 32-bit compatibility libraries be installed.

32-bit and 64-bit Versions

On UNIX and Macintosh Intel platforms that provide 64-bit support, you can run IDL, ENVI, ENVI Zoom, or ENVI EX as either a 32-bit or a 64-bit application. When both versions are installed, the 64-bit version is the default. You can run the 32-bit version by specifying the -32 switch at the command line, as follows:

% idl -32  
% idlde -32 
% envi -32 
% envizoom -32 
% enviex -32 

On Windows, the 32-bit and 64-bit versions are started via separate Start menu entries.
On Macintosh Intel 64-bit machines, you can double-click on the 32-bit Macintosh Applescript (.app) files.

Graphics Hardware

Some IDL, ENVI Zoom, and ENVI EX features take advantage of graphics hardware that supports the OpenGL 2.0 interface to improve rendering performance, if such hardware is present. Your video card should support OpenGL 2.0 or higher to take advantage of these features. Be sure to update your video card drivers with the most recent version.

Platform Support Questions and Answers

This topic describes the platform support requirements for IDL 7.1 and ENVI 4.7. Platform support requirements change over time; for the most current information, visit the ITT Visual Information Solutions web site: http://ittvis.com/ProductServices/IDL/PlatformSupport.aspx.

Software Requirements

IDL, ENVI, ENVI Zoom, and ENVI EX require the following software:

Table 1-2: Software Requirements for IDL and ENVI


Software Requirements


Internet Explorer 5.0 or higher


Apple X11 X-Windows manager

Feature Support by Operating System

IDL Features

The following table shows marks indicating which platforms support the corresponding feature. IDL technologies not listed in this table are assumed to work on all supported platforms.


Table 1-3: Feature Support: IDL 7.1 
















ActiveX: WIDGET_ACTIVEX (IDLcomActiveX object)

COM Object –Export (via Export Bridge Assistant)

COM Object –Import (IDLcomIDispatch object)


DICOM Network Services

DICOM Read/Write (IDLffDicomEx object)

DICOM Read (IDLffDicom object)

DXF file format (IDLffDXF object)

IDL Advanced Math and Stats
(IMSL Numerical Library)


Remote Procedure Calls (RPCs)

IDL Workbench and Online Help

ENVI Features

The following table shows marks indicating which platforms support the corresponding feature. These features are in addition to those listed in IDL Features. ENVI technologies not listed in this table are assumed to work on all supported platforms.


Table 1-4: Feature Support: ENVI 4.7















Atmospheric Correction Module: QUAC and FLAASH (ENVI)

Tape utilities (ENVI)

Reading ECW files (ENVI)

Reading and writing ESRI® GRID files (ENVI)

Reading and writing ESRI® GRID files (ENVI Zoom and ENVI EX)


Reading MrSID files (ENVI)

Reading MrSID files (ENVI Zoom and ENVI EX)

RemoteView link (ENVI)

Opening files in ArcMap™ software (all products) b

ArcGIS® geodatabase support
(all products):b
Connect to and read from geodatabase
Save to file or personal geodatabase
Save to enterprise SDE geodatabase

Chip to PowerPoint® software (ENVI Zoom and ENVI EX)

Map Layout view (File Print in ENVI Zoom and ENVI EX) e

IAS and JPIP (all products)

NITF (all products) e

TFRD module (all products)

ENVI Orthorectification Module



a Windows users: these ENVI functions only run in 32-bit mode. If you have a 64-bit Windows PC and you want to use these functions, run ENVI in 32-bit mode as follows from the Windows Start menu: Program Files ENVI x.x → 32-bit ENVI or ENVI + IDL or ENVI Zoom.
b Supported on ArcGIS® Desktop 9.2 and later; tested on Windows XP 32-bit and Vista 32-bit with ArcGIS® Desktop 9.3.
c Requires ArcInfo® or ArcEditor™ license (ArcView® does not support this feature).
d Not supported on Macintosh OS X 10.4 platforms.
e In order to display NITF files in the File > Print dialog in ENVI Zoom and ENVI EX, NITF for ArcGIS must be installed.

What is ENVI?
ENVI is the ideal software for the visualization, analysis, and presentation of all types of digital imagery. ENVI's complete image-processing package includes advanced, yet easy-to-use, spectral tools, geometric correction, terrain analysis, radar analysis, raster and vector GIS capabilities, extensive support for images from a wide variety of sources, and much more.
ENVI's unique approach to image processing combines file-based and band-based techniques with interactive functions. When you open a data input file, its bands are stored in a list where you can access them from all system functions. If you open multiple files, you can process bands of disparate data types as a group. ENVI's interactive analysis capabilities include:

  • Multiple dynamic overlay capabilities that allow easy comparison of images in multiple displays.
  • Real-time extraction and linked spatial/spectral profiling from multispectral and hyperspectral data that provide you with new ways of looking at high-dimensional data.
  • Interactive tools to view and analyze vectors and GIS attributes.
  • Standard capabilities, such as contrast stretching and 2D scatter plots.

ENVI's interface is complemented by its comprehensive library of processing algorithms. ENVI includes all the basic image processing functions. ENVI does not impose limitations on the number of spectral bands that you can process, so you can use either multispectral or hyperspectral data sets. ENVI also includes advanced tools for analyzing radar data sets.
ENVI addresses common image processing problem areas such as input of non-standard data types, viewing and analysis of large images, and simple extensions of analysis capabilities (add-on functions). The software includes essential tools required for image processing across multiple disciplines, and it has the flexibility to allow implementation of customized analysis strategies.
ENVI is written in IDL (Interactive Data Language), a powerful structured programming language that offers integrated image processing. The flexibility of ENVI is due largely to IDL's capabilities.
There are two types of ENVI licenses:

  • ENVI + IDL: ENVI plus a full version of IDL
  • ENVI: ENVI plus a runtime version of IDL

ENVI + IDL users can use IDL to customize their own command-line functions. Advanced ENVI + IDL users should find the flexibility offered by IDL's interactive features helpful for their dynamic image analyses.

About ENVI Functionality
ENVI simplifies comprehensive interactive processing of large multiband data sets, screen-sized images, spectral plots and libraries, and image regions of interest (ROIs), while providing flexible display capabilities and geographic-based image browsing. ENVI provides a multitude of interactive functions, including:

  • x,y,z profiling
  • Image transects
  • Linear and non-linear histogramming and contrast stretching
  • Color tables
  • Density slicing
  • Classification color mapping
  • Quick filter preview
  • ROI definition and processing
  • Vector creation and display

ENVI provides methods for locating specific pixels and for interactive spatial/spectral pixel editing. It also offers interactive scatter plot functions, including 2D dancing pixels and the n-Dimensional Visualizer. With ENVI, you can interactively link images together and create dynamic overlays, create comprehensive vector overlays with GIS attributes, and add map grids as well as annotations to images. Other ENVI interactive functions include 3D (perspective) viewing and fly-through animation, surface shading, and geometric rectification and mosaicking.
ENVI functionality works with full data files and subsets. It provides a complete set of tools to process panchromatic images, AVHRR, Landsat TM, ASTER, MODIS, QuickBird, WorldView-1, IKONOS, Orbview-3, and ENVISAT data, as well as dozens of other data types. ENVI is also capable of processing many other multispectral and hyperspectral images, and data from advanced SAR systems.
End-to-End Processing
ENVI includes tools for complete end-to-end processing of any type of remotely sensed imagery. From orthorectification to information extraction to integration with geographic information systems (GIS), ENVI combines all the tools you need for any type of project.
Hyperspectral Data Analysis
ENVI provides a full suite of tools for processing hyperspectral data. Developed by experts in the field, ENVI's spectral analysis tools are unequaled. Among others, ENVI provides tools for:

  • Sub-pixel analysis
  • Feature extraction
  • Spectrum identification
  • Anomaly detection
  • Mapping of materials
  • Target finding

About ENVI Zoom

ENVI Zoom is a simplified, yet powerful, version of ENVI that lets you display and manipulate remote sensing images, vectors, and annotation, with ease and efficiency. The interface provides quick access to common display tools such as contrast, brightness, sharpening, and transparency. You can also re-project and re-sample images and vectors on-the-fly. ENVI Zoom provides tools to help you keep track of multiple data sets and their properties, and it includes a Portal viewer to let you see multiple data sets at once. ENVI Zoom also contains the robust RX Anomaly Detection, Pan Sharpening, and Vegetation Suppression tools.


ENVI EX is ENVI's image processing and analysis solution for GIS users. ENVI EX includes advanced image manipulation tools that allow you to interactively visualize your data.
With ENVI EX, you can perform image processing tasks like pan sharpening, vegetation suppression, and anomaly detection quickly and easily from the ENVI EX toolbox.
The ENVI EX automated image analysis workflows take the complexity out of image processing. They provide step by step procedures and instructions to guide you through orthorectifying images, detecting change in an area over time, finding features of interest over a wide area, and classifying land cover. All of the processing and analysis tools in ENVI EX are based on ENVI's scientific algorithms and methods.

ENVI Add-On Modules

ITT Visual Information Solutions offers several add-on modules to extend ENVI's functionality. User documentation for each are included in PDF format on the ENVI Resource DVD (included with your software), and in the ENVI Help. Each module requires an additional license in your installation; contact your ENVI sales representative to obtain a license.

DEM Extraction

The ENVI Digital Elevation Model (DEM) Extraction Module enables you to extract elevation data from pushbroom stereo images, such as those from the ALOS PRISM, ASTER, CARTOSAT-1, FORMOSAT-2, GeoEye-1, IKONOS, KOMPSAT-2, OrbView-3, QuickBird, WorldView-1, and SPOT satellites. The DEM Extraction Module includes the DEM Extraction Wizard and three DEM tools the DEM Editing Tool, Stereo Pair 3D Measurement Tool, and Epipolar 3D Cursor Tool.
See the DEM Extraction Module User's Guide for details about using the DEM Extraction Module.

ENVI Orthorectification

The ENVI Orthorectification Module allows you to build highly accurate orthorectified images by rigorously modeling the object-to-image transformation. The details of this transformation are mostly transparent, which means you can quickly create orthorectified images without defining any detailed model parameters.
For more information, see the ENVI Orthorectification Module User's Guide.

Atmospheric Correction: QUAC and FLAASH

For those interested in quantitative analysis of surface reflectance, removing the influence of the atmosphere is a critical pre-processing step. ENVI's Atmospheric Correction Module provides two options: Quick Atmospheric Correction (QUAC) and Fast Line-of-sight Atmospheric Analysis of Spectral Hypercubes (FLAASH).
The Atmospheric Correction Module allows you to accurately remove the obscuring effects of the atmosphere. QUAC and FLAASH were developed by Spectral Sciences, Inc., a world leader in optical phenomenology research, in collaboration with U.S. Air Force Research Laboratory (AFRL) and Spectral Information Technology Application Center (SITAC) personnel.
See the Atmospheric Correction Module User's Guide for details about using QUAC and/or FLAASH.


The ENVI National Imagery Transmission Format (NITF) and NATO Secondary Image Format (NSIF) Module and NITF for ArcGIS® support reading and writing image files in the NITF and NSIF formats. The NITF/NSIF Module and NITF for ArcGIS provide compliant NITF software environments that take advantage of ENVI's image analysis capabilities. With the NITF/NSIF Module and NITF for ArcGIS, ENVI and ArcMap™ can read and display all compressed or uncompressed NITF version 2.0 and 2.1 and NSIF 1.0 files, as well as legacy NITF 1.1 files, and write NITF version 2.0 and 2.1 and NSIF 1.0 files.
See the NITF/NSIF Module User's Guide for details about using the NITF/NSIF Module.
The NITF for ArcGIS license is included with the NITF Module license. It can also be purchased separately at additional cost from ITT Visual Information Solutions, ESRI®, or your ENVI Distributor. If you have ArcGIS 9.3 or later installed, you can license NITF then install and run NITF for ArcGIS. NITF for ArcGIS provides the ability to read NITF data within the ArcGIS environment and create data products with ArcGIS Desktop that comply with the latest NITF specifications.
ENVI also supports reading TFRD files, but requires a separate module license and install. These can be obtained by contacting ITT Visual Information Solutions.

Additional ENVI Documentation
ENVI provides the following documentation in addition to this guide. Most of the documentation is available as a download from the ITT Visual Information Solutions website and/or on the ENVI Resource DVD, which is included with your installation package.

  • ENVI Help
    A compilation of all of the ENVI documentation in a searchable help format. ENVI Help is included with your ENVI installation, and you can access it by selecting Help → Start ENVI Help from the ENVI main menu bar. For Windows, you can optionally access Help by selecting Programs → ENVI x.x → ENVI Help from the Windows Start menu. For UNIX, you can optionally access ENVI Help by typing either envihelp, envi_tut, or envi man at the UNIX prompt (your environment variables must be appropriately set up).
  • ENVI Zoom Help
    The ENVI Zoom User's Guide in a searchable help format. ENVI Zoom Help is included with your ENVI Zoom installation, and you can access it by selecting Help from the ENVI Zoom menu bar.
  • Installation and Licensing Guide
    Describes how to install and license ENVI on your machine.
  • ENVI User's Guide
    Provides step-by-step instructions for working with ENVI.
  • ENVI Zoom User's Guide
    Provides step-by-step instructions for working with ENVI Zoom.
  • ENVI Programmer's Guide
    Provides sample code and instructions on programming in ENVI.
  • ENVI Reference Guide
    Alphabetically documents all ENVI library routines. Each routine includes a description, the syntax, arguments (if any), keywords (if any), and an example of using the routine.
  • ENVI Tutorials
    Provides tutorials designed to lead a new user through ENVI's basic and advanced functionality. You need a free customer login to access tutorials from the ITT Visual Information Solutions website. Tutorials are also provided in PDF format on the ENVI Resource DVD included with your ENVI installation.
  • ENVI DEM Extraction Module User's Guide
    Describes how to use the DEM Extraction Module.
  • ENVI Orthorectification Module User's Guide
    Describes how to use the Orthorectification Module.
  • ENVI Atmospheric Correction Module User's Guide
    Describes how to use the Atmospheric Correction tools QUAC and FLAASH.
  • ENVI NITF/NSIF Module User's Guide
    Describes how to use the NITF/NSIF Module.

If you purchased an ENVI + IDL license, the following IDL documentation is available:

  • IDL Online Help
    Provides all of the IDL documentation, compiled into a searchable help format. IDL Online Help is included with your ENVI + IDL installation and is accessed by selecting Help → Contents from the IDL main menu bar.
  • Using IDL
    Provides the basics of using IDL. This document is included in IDL Online Help.
  • IDL Reference Guide
    Alphabetically documents all IDL Functions and procedures. This document is included in IDL Online Help.

ENVI Support

If you experience a problem with ENVI, first verify that the issue is not a result of misinterpreting the expected outcome of a specific function or action. Double-check the ENVI documentation and ENVI Help, or check with a local expert. Make sure your system is properly configured with enough virtual memory and sufficient operating system quotas.
If the problem still occurs, report it to Technical Support quickly, so that the issue can be resolved, or a workaround can be provided. If you cannot find the information you need in the ENVI documentation or ENVI Help, report this to Technical Support as well, so that the documentation can be updated.

Contacting Technical Support

To report a problem, you can call, e-mail, or go online to submit a Support Incident:
Technical Support Direct: 303-413-3920
E-Mail: support@ittvis.com
Internet: Go to www.ittvis.com and select Support → Technical Support.
ITT Visual Information Solutions
4990 Pearl East Circle
Boulder, CO 80301 USA
Phone: 303-786-9900
Fax: 303-786-9909

Contacting Sales

Contact ITT Visual Information Solutions Sales to purchase add-on module licenses or additional ENVI licenses:
ITT Visual Information Solutions
4990 Pearl East Circle
Boulder, CO 80301 USA
Phone: 303-786-9900
Fax: 303-786-9909
E-Mail: sales@ittvis.com

Training and Custom Development Services

ITT Visual Information Solutions has a team of Professional Services Group (PSG) consultants who provide custom software development, consulting services, and training to commercial, research, and government markets. The PSG team can either help you define requirements and lead your development cycle from prototyping to final installation, or they can join your project mid-stream and provide expert assistance.
Each PSG team member offers expertise in areas such as image processing; data analysis; visualization; software development; a broad range of scientific application areas; and government civilian, defense, and intelligence community requirements. If needed, ITT Visual Information Solutions has staff with the necessary security clearances to support classified projects.
The PSG team is experienced in extending ENVI's robust suite of user functions and batch programming capabilities, and has up-to-date knowledge on recent product enhancements and future product direction. Their contact information is as follows:
Professional Services Group
ITT Visual Information Solutions
4990 Pearl East Circle
Boulder, CO 80301 USA
Phone: 303-786-9900
Fax: 303-786-9909
E-Mail: sales@ittvis.com

ENVI Training

ITT Visual Information Solutions offers training courses designed to teach users about ENVI functions. ITT Visual Information Solutions teaches regularly scheduled ENVI courses at our training facility in Boulder, Colorado. In addition, ITT Visual Information Solutions offers regional training classes every year at various locations in the United States, Europe, and Australia. For the latest training schedule, a detailed course outline, or the cost of a training course, call, send e-mail, or go online:
Phone: 303-786-9900 (ask for Training)
Fax: 303-786-9909
E-Mail: training@ittvis.com
Internet: Go to www.ittvis.com and select Events and Training.

Additional Resources

There are two additional resources for ENVI support, the ITT Visual Information Solutions website and the IDL newsgroup.

ITT Visual Information Solutions Website

The ITT Visual Information Solutions website has several links that provide additional ENVI support. The website includes access to user-contributed ENVI code, an ENVI user forum, an IDL user forum, and technical tips. Go to www.ittvis.com and select User Community to select an option.

IDL Newsgroup

The Usenet newsgroup comp.lang.idl-pvwave is dedicated to the discussion of IDL. Users post questions and answers and share information about their own IDL projects. Note that many ITT Visual Information Solutions employees read this newsgroup, but do not usually post messages to the group.
Send problem reports and technical support questions to ITT Visual Information Solutions via phone or e-mail. See Contacting Technical Support.

Starting and Exiting ENVI

Before starting ENVI, ensure that it is properly installed, as described in the Installation and Licensing Guide. The Installation and Licensing Guide also provides steps to start ENVI on Windows, UNIX, and Macintosh.

Using Startup Scripts

Use startup scripts in ENVI to automatically open image files, to load bands into displays, to open vector files, and to open region of interest (ROI) files. You can configure your ENVI preferences to run a script at ENVI startup, or you can run a script manually from the ENVI main menu bar. The format for the startup script is described below.
To configure your ENVI preferences to run a startup script each time you start ENVI, see User-Defined File Preference Settings in the ENVI User's Guide.
To run a startup script manually:

  1. From the ENVI main menu bar, select File → Execute Startup Script. The Input Script Filename dialog appears.
  2. Select the startup script filename.
  3. Click Open.

Startup Script Format

Create a startup script using a text editor and name the file using the extension .ini. The available startup commands and their formats are as follows:

Table 2-1: Startup Script Command Syntax 


Command Syntax

Open an image file

open file = filename

Load a gray scale image into a new display group

load band = band_number
The band number refers to the file opened in the line above the load band command.

Load an RGB color image into a new display

load bands = R_band_number, G_band_number, B_band_number
The band numbers refer to the file opened in the line above the load band command.

Open an ENVI vector file (.evf)

open evf = evf_filename

Open an ROI file

open roi = roi_filename

Open a saved display group

open display group = display_group_filename

Example Startup Script

open file = e:\data\canyon\canyon.tm 
load bands = 4,3,2 
open file = e:\data\canyon.tif 
load band = 1 
open roi = e:\data\canyon\canyon.roi 

Saving a Session to a Script

Use Save Session to Script to save currently open image files and their bands, and display groups to an ENVI startup script. To execute this startup file, see Using Startup Scripts.
The Save Session to Script option only works for files that you can open through the ENVI main menu bar option File → Open Image File (see Opening Image Files in ENVI).

  1. From the ENVI main menu bar, select File → Save Session to Script. The Output ENVI Script Filename dialog appears.
  2. Enter the startup filename (typically with the extension .ini).

Exiting ENVI

  1. Save any open files or in-memory items you wish to keep.
  2. From the ENVI main menu bar, select File → Exit. ENVI closes all open files and in-memory items and exits.

ENVI Image Files

ENVI uses a general raster data format consisting of a simple flat binary file and a small associated ASCII (text) header file. This enables ENVI's flexible use of nearly any image format, including those with embedded header information. Because ENVI uses ASCII header files that are built on-the-fly if required, you typically do not need to convert your image file formats. ENVI supports MSS, TM, SPOT, ERS-1, AVHRR, AVIRIS, GERIS, GEOSCAN, TIMS, digitized aerial photographs, DEM data, AIRSAR, RADARSAT, and SIR-C data in their native formats (byte, signed and unsigned integer, long integer, floating point, double precision, 64-bit integer, unsigned 64-bit integer, complex, or double complex). The general raster data is stored as a binary stream of bytes either in Band Sequential Format (BSQ), Band Interleaved by Pixel Format (BIP), or Band Interleaved by Line Format (BIL) formats.


BSQ format is the simplest format, where each line of the data is followed immediately by the next line in the same spectral band. This format is optimal for spatial (x,y) access of any part of a single spectral band.


BIP format stores the first pixel for all bands in sequential order, followed by the second pixel for all bands, followed by the third pixel for all bands, and so forth, interleaved up to the number of pixels. This format provides optimum performance for spectral (z) access of the image data.


BIL format stores the first line of the first band, followed by the first line of the second band, followed by the first line of the third band, interleaved up to the number of bands. Subsequent lines for each band are interleaved in similar fashion. This format provides a compromise in performance between spatial and spectral processing and is the recommended file format for most ENVI processing tasks.

ENVI Header Files
The ENVI header file is a separate text file that contains information ENVI uses to read an image data file. It is typically created the first time ENVI accesses a data file. The header file provides the following information:

  • The dimensions of the image
  • The imbedded header, if present
  • The data format
  • Other pertinent information

If the image file does not already have a header file, you enter the required header information interactively (see Creating Header Files). You can also edit the header file later (see Editing Header Files). If needed, you can generate an ENVI header using a text editor (see The ENVI Header Format).

ENVI File Naming Conventions

ENVI does not impose any constraints on filenames, with the exception of the use of the.hdr extension used for header files. Some ENVI functions pre-load lists of files with specific extensions for ease of use (see below). Use these extensions consistently when running ENVI to maximize file handling efficiency. (This does not preclude you from using different filenames, if desired.)

Table 2-2: ENVI File Types 

File Type


ENVI bad lines list


ENVI Band Math or Spectral Math expression


ENVI calibration factors


ENVI contour levels file


ENVI density slice range file


ENVI display group


ENVI filter kernels




ENVI grid file


ENVI header file


ENVI image

None defined

ENVI look up table


ENVI map key


ENVI mosaic template file


ENVI n-D visualizer state


ENVI PPI count file


ENVI region of interest


ENVI spectral library


ENVI startup script


ENVI statistics file


ENVI statistics report


ENVI surface view path file


ENVI tape script


ENVI vector file


ENVI vector template file


JPL AIRSAR compressed stokes matrix radar data


SIR-C compressed data product


Cross-Platform File Portability for Header Files

When naming files in ENVI, consider cross-platform portability. This is particularly important for preserving the relationship between image files and their corresponding header files.
On UNIX, ENVI appends the image filename with .hdr when creating a header file, so a UNIX image file named image_1.img has a header file named image_1.img.hdr. If two image files have the same name but different extensions (for example, .img and .dat), the corresponding header filenames are image_1.img.hdr and image_1.dat.hdr.
On Windows, ENVI replaces the image file extension with .hdr when creating a header file, so a Windows image file named image_1.img has a header file named image_1.hdr. If there are two image files with the same name but different extensions (for example, .img and .dat), the files would have the same header filename of image_1.hdr. This could cause problems in ENVI if the two images are located in the same directory and have different sizes and characteristics.
If cross-platform portability of images is an issue, the easiest solution is not to name image files with an extension. As a result, an image file has the same header filename in both UNIX and Windows. Alternatively, you can rename images and header files to the Windows convention before moving the images from UNIX to Windows systems.

ENVI Supported Input File Formats

  • AVHRR Formats: KLMN/Level 1b, Quorum, SHARP
  • EOS Formats: ASTER, MODIS
  • EROS A Formats: Level 1A, Level 1B (GeoTIFF)
  • Flat Binary Formats: BSQ, BIL, BIP
  • Generic Formats: ASCII, HDF, JPEG, JPEG2000, MrSID, PDS, PICT, PNG, SRF, TIFF/GeoTIFF1, GeoTIFF with metadata (.txt and .met), TIFF world files (.tfw), XWD
  • GeoEye-1 Formats: GeoTIFF, NITF
  • IKONOS Formats: GeoTIFF, NITF
  • Image Processing Software Formats: ArcView® Raster (.bil), ECW, ERDAS IMAGINE, ER Mapper, ESRI® GRID, PCI (.pix)
  • IRS Formats: Fast, SuperStructured
  • KOMPSAT-2 Formats: GeoTIFF
  • Military Formats: ADRG, CADRG, CIB, NITF, miscellaneous formats, ATSR, DMSP (NOAA), LAS LIDAR, OrbView files, GeoTIFF, NITF
  • QuickBird Formats: GeoTIFF, NITF, QuickBird Tile Products (.til)
  • RapidEye: GeoTIFF, NITF
  • SeaWIFS Formats: CEOS, HDF
  • SPOT Formats: ACRES SPOT, DIMAP, GEOSPOT, SPOT, Vegetation
  • TFRD: (You must purchase a separate module through ITT Visual Information Solutions.)
  • Thermal Formats: AATSR, ASTER, MASTER, TIMS
  • USGS and Digital Elevation Formats: USGS DRG, USGS DOQ, USGS DEM, SDTS DEM, DTED, SRTM DEM
  • Vector Formats: ArcInfo® interchange format, shapefile, DXF, ENVI vector file (.evf), MapInfo Interchange, Microstation DGN, USGS DLG, USGS DLG in SDTS format
  • WorldView-1 Formats: GeoTIFF, NITF, WorldView-1 Tile Products (.til)

1ENVI supports the following input TIFF compression formats CCITT Group 3 and 4 algorithms, Macintosh PackBits algorithm, ThunderScan 4-bit RLE algorithm, NeXT 2-bit RLE algorithm, and LogLuv high dynamic range encoding.

ENVI Supported Output File Formats

  • ENVI Flat Binary Formats: BIL, BIP, BSQ
  • Generic Image Formats: ASCII, BMP, HDF, JPEG, JPEG 2000, PICT, PNG, TIFF (GeoTIFF), TIFF world (.tfw), SRF, XWD
  • Image Processing Formats: ArcView® raster (.bil), ER Mapper, ERDAS IMAGINE, ESRI® GRID, NITF 02.00/02.10, PCI (.pix)
  • Vector Formats: shapefile, DXF, ENVI vector file (.evf)


Source: ENVI 4.7 Help