ENVI format

ENVI is a famous commercial software for remote sensing analysis.

Even if you don't use the software, ENVI format is useful for you.

Details are in this site: http://www.harrisgeospatial.com/docs/ENVIHeaderFiles.html

Data with ENVI format consists of two parts: a raster raw data file and a header file. If the filename of the raster raw data is "abcd", then the filename of the header file must be "abcd.hdr". In combination of these two files, GIS softwares such as QGIS can import your data.

A raster raw data is easy. Just a matrix of digital number.

A header file needs to follow a set of format rule. It is like

ENVI
description = {out}
samples = 7200
lines   = 1600
bands   = 1
header offset = 0
file type = ENVI Standard
data type = 12
interleave = bsq
byte order = 0
map info = {Geographic Lat/Lon, 1, 1, -180, 40, 0.05, 0.05}
coordinate system string = {
GEOGCS["GCS_WGS_1984",
DATUM["D_WGS_1984",
SPHEROID["WGS_1984",6378137.0,298.257223563]],
PRIMEM["Greenwich",0.0],
UNIT["Degree",0.017453292519943295]]}
band names = {Band 1}

You should change the value of "data type" depending on your data:

   1 = Byte: 8-bit unsigned integer
   2 = Integer: 16-bit signed integer
   3 = Long: 32-bit signed integer
   4 = Floating-point: 32-bit single-precision
   5 = Double-precision: 64-bit double-precision floating-point
   6 = Complex: Real-imaginary pair of single-precision floating-point
   9 = Double-precision complex: Real-imaginary pair of double precision floating-point
   12 = Unsigned integer: 16-bit
   13 = Unsigned long integer: 32-bit
   14 = 64-bit long integer (signed)
   15 = 64-bit unsigned long integer (unsigned)

map info:

   Projection name
   Reference (tie point) pixel x location (in file coordinates)
   Reference (tie point) pixel y location (in file coordinates)
   Pixel easting
   Pixel northing
   x pixel size
   y pixel size
   Projection zone (UTM only)
   North or South (UTM only)
   Datum
   Units

Note: 0.017453292519943295 in UNIT is pi/180.