elasinfo(1)

PROGRAM
elasinfo - Reads and prints an ELAS file format header.

SYNTAX

elasinfo

-i  input ELAS data file

[-f]
    output ascii file

[-V]
    Gives the version for elasinfo

[-U]
    Gives the usage for elasinfo

[-P]
    Prompts for command line options

[-A [file1]]
    Creates the answer file called elasinfo.ans or file1

[-a [file1]]
    Uses elasinfo.ans or file1 as the answer file

DESCRIPTION
elasinfo is a routine that reads and prints an ELAS image file format header. The ELAS image file format describes the image format used by the ELAS Image system.

Record 1 contains all the header information. The remaining records, beginning with record 2 store image data one scanline at a time in (BIL) band-interleaved-by-line format for any number of bands. Each record contains one scan line of one channel, thus each record corresponds to a new scan line for a particular channel.

The Band-Interleaved-By-Line order means that the first scanline of the first band is stored first. It is followed by the first scanline of the second band, third band, fourth band, and so on up to the last band avaliable. This order then repeats for the second scanline, the third scanline and so on.

The format is according to the following scheme:
     Record Number         Data Description
     ------------          ----------------
           1               Header Record
           2               Scan line 1, channel 1
           3               Scan line 1, channel 2
           4               Scan line 1, channel 3
           5               Scan line 2, channel 1
           6               Scan line 2, channel 2
           .                        .
           .                        .
           .                        .

Note that the terminology for band and channel is used interchangably, The term band is typically used in the conventional image processing community, while channel is commonly used in the remote sensing community. Scan line here refers to one row of the image.

The image header for the ELAS image file format is as follows:
 BYTES      TYPE                DESCRIPTION
-------     ----    -------------------------------------------
[1-4]       int     (NBIH) Number of bytes in header.
[5-8]       int     (NBPR) Number of bytes per record.
[9-12]      int     (IL)   Initial line of data file.
[13-16]     int     (LL)   Last line of data file.
[17-20]     int     (IE)   Initial element of each scan line.
[21-24]     int     (LE)   Last element of each scan line.
[25-28]     int     (NC)   Number of channels (bands).
[29-32]     int     (4321) Header record identification.
[33-36]     ASCII   Grid descriptor for Y-axis: NOR, LSNL, etc.
[37-40]     int     Y-Offset: Y-coordinate value for scan line 0.
[41-44]     ASCII   Grid descriptor for X-axis: EAS, LNSE, etc.
[45-48]     int     X-Offset: X-coordinate value for element 0.
[49-52]     float   Y Spot size, or pixel element height.
[53-56]     float   X Spot size, or pixel element width.
[57-72]     float   Transformation matrix (linear) from line and
                     column (IL, LL, IE, LE) coordinates to the
                     coordinates described by the grid descriptors.
                       1., 0., 0., 1. =  identity transformation
                       1., 0., 0., -1. = data in UTM format
[73-84]     ---     Not Used.
[85-88]     int     (Eikonix) Used by modules RFEKDA and VEKS.
[89-92]     int     (LABL) Used by module LABL.
[93-96]     ASCII   (HEAD) Used by module HEAD.
[97-480]    ASCII   Comments - 6 lines at 64 characters each or
                     96 4-character descriptiors for data base use.
[481-992]   int     Color Table (color map)
[993-1024]  ---     Not Used.
IMPORTANT

The utilities used to read and write the ELAS image file are machine dependent. WE ASSUME THAT THE ELAS IMAGE WILL ALWAYS BE IN LITENDIAN BYTE FORMAT. This means that a machine that uses bigendian byte order (i.e. sun, sony, etc) must byte swap some fields in the image header. So, the code allows conversion between litendian byte order and bigendian byte order.

The only file that has machine dependencies is elas.c in the file_formats library (libfile_formats.a).

1. The not define flag
    This routine can be compiled so that it is not machine dependent by using -DNMD option. NMD stands for not machine dependent. When compiled with this option the bigendian to litendian conversion is not performed.

2. defines for machine dependencies
    The defines for machine dependencies (conversion to and from bigendian) are sun, bigendian, and ieeeorder. So elas.c can be compiled with -Dbigendian. Note, when compiling on a sun machine, sun is defined so the conversion code from bigendian to litendian will be be compiled. If it is unwanted see 1. above.

REQUIRED ARGUMENTS

-i  type: infile
    desc: input ELAS data file

OPTIONAL ARGUMENTS

-f  type: outfile
    desc: output ascii file

EXAMPLES
elasinfo -i image.elas -f image.info

This will read an image in the ELAS image file format and print out the header information to the specified file in ASCII format.

elasinfo -i image.elas -f #

This will read an image in the ELAS image file format and print out the header information to the standard output device.

SEE ALSO
intro(1), verror(3), vgparms(3), vutils(3), lelasinfo(3)

RESTRICTIONS

COPYRIGHT
Copyright 1991, University of New Mexico. All rights reserved.