Glossary

bands

Refers to the spectral dimension of hyperspectral images.

BIL

Band interleaved by line memory ordering. A type of interleave.

BIP

Band interleaved by pixel memory ordering. A type of interleave.

BSQ

Band sequential memory ordering. A type of interleave.

dark reference

A dark reference image of the same format as the hyperspectral image sensor, typically an average of many repeated samples. The image is taken with a cap in front of the camera. For pushbroom cameras, the image contains the spectral and one spatial axis.

ENVI

The most widespread file format developed specifically for hyperspectral data. It was developed by NV5 Geospatial for their processing software.

ENVI uses a versatile header format that supports arbitrary metadata. The image data itself is not compressed or encoded.

interleave

Refers to the memory layout of a hyperspectral data cube, specifically one of BSQ, BIL, or BIP.

lines

Refers to the y-axis of hyperspectral images. The term comes from pushbroom cameras, where each individual image represents a single line.

PAM

A highly generic image format that can also be used for hyperspectral data. The SDK uses some unofficial values in the header to support all interleave types.

reflectance calibration

A conversion of raw image values to pseudo-reflectance values. This is performed using the formula: \(R = \frac{I - D}{W - D}\), where \(I\) is the original image, \(D\), \(W\) are the dark and white references

samples

Refers to the x-axis of hyperspectral images. The term comes from pushbroom cameras, where each individual image consists of a number (the width of the image) of spectral samples.

Tiff

An popular image format that can also support hyperspectral data.

For hyperspectral purposes, tiff is useful because it supports compression and the files can be viewed in many different image viewers (they have to support multi-image tiff files).

white reference

A white reference image of the same format as the hyperspectral image sensor, typically an average of many repeated samples. The image is taken by pointing at a white calibration target. For pushbroom cameras, the image contains the spectral and one spatial axis.