GENHASH

Description

GENHASH generates image, bitmap, or vector segment hash values and appends these to a checksum file to be used with CHKHASH.

Parameters

Name	Type	Caption	Length	Value range
TFILE*	String	Text file name	1 - 192
FILE*	String	Input file name	1 - 192
HASHOPT	String	Vector hash options	0 - 64	Default: ALL
DBIC	Integer	Input raster channel(s)	0 -
DBIB	Integer	Input bitmap channel(s)	0 -
DBVS	Integer	Input vector segment(s)	0 -
DBIW	Integer	Raster input window	0 - 4	Xoffset, Yoffset, Xsize, Ysize
MONITOR	String	Monitor mode	0 - 3	ON, OFF Default: ON

* Required parameter

Parameter descriptions

TFILE

Specifies the name of the text file into which the image filename, channels, window, and checksum data should be written. This file is used as input to CHKHASH.

FILE

Specifies the name of the GDB-supported file containing the image data for which to compute hash numbers.

HASHOPT

Defines the type of hash value to be computed for vectors. This is passed on to VECHASH, although the EACH option only has meaning to GENHASH.

Running GENHASH with a HASHOPT of EACH is equivalent to running GENHASH for the set of vectors with a HASHOPT of VERTICES, then ATTRIBUTES, then RST, then SCHEMA, then PROJ, then ALL. Unlike VECHASH, multiple HASHOPT values cannot be set in one call; for example, HASHOPT = "SCHEMA ATTRIBUTES" will cause an error.

DBIC

Specifies the channel(s) in the input file to be processed.

Ranges of channels or segments can be specified with negative values. For example, {1,-4,10} is internally expanded to {1,2,3,4,10}. When you are not specifying a range in this way, only 48 numbers can be specified explicitly.

DBIB

Specifies the bitmap channel(s) in the input file to be processed.

Ranges of channels or segments can be specified with negative values. For example, {1,-4,10} is internally expanded to {1,2,3,4,10}. When you are not specifying a range in this way, only 48 numbers can be specified explicitly.

DBVS

Specifies the input vector segment(s) to be processed.

Ranges of channels or segments can be specified with negative values. For example, {1,-4,10} is internally expanded to {1,2,3,4,10}. When you are not specifying a range in this way, only 48 numbers can be specified explicitly.

DBIW

Specifies the raster window (Xoffset, Yoffset, Xsize, Ysize) that is read from the input layers. If DBIW is not specified, the entire layer is used by default. Xoffset, Yoffset define the upper-left starting pixel coordinates of the window. Xsize is the number of pixels that define the window width. Ysize is the number of lines that define the window height.

MONITOR

The program progress can be monitored by printing the percentage of processing completed. A system parameter, MONITOR, controls this activity.

Available options are:

• ON: Turns the monitor ON (default)
• OFF: Turns the monitor OFF (recommended if running in batch or background mode)

Details

GENHASH generates a text file containing file checksums to test using CHKHASH. The checksums are computed using IMGHASH, BITHASH, VECHASH and PROHASH. GENHASH is provides a convenient method of writing the checksums into a file in the format required by CHKHASH.

A projection hash value is generated only if no other hash values are requested; that is, if DBIC, DBIB, and DBVS are all defaulted.

Any GDB-supported format can be used as input. The use of the FILE, DBIC, and DBIW parameters are similar to those used in IMGHASH, except that DBIC may be specified in "channel list" format.

The text file generated contains either three or seven fields. The first field is the file name, the second is the channel number, and the third is the checksum for that channel. An optional four fields indicating a subwindow follow the checksum.

Detail lines are also written to the screen, displaying the information that is placed in the file.

Example

Generate a hashing test file for all channels of all the standard demo files.

EASI>tfile = "pcidemo.hsh"
EASI>file = "/demo/irvine.pix"
EASI>dbic = 1,2,3,4,5
EASI>dbib = 9,10,11,12
EASI>dbvs = 25,26
EASI>hashopt = "all"
EASI>dbiw=
EASI>run genhash                      ! Image, bitmap, vector hash
 
EASI>dbic =
EASI>dbib =
EASI>dbvs =
EASI>run genhash                      ! Generate projection hash

EASI>file = "/demo/eltoro.pix"
EASI>dbic = 1
EASI>run genhash                      ! Generate image hash

EASI>dbic =
EASI>run genhash                      ! Generate projection hash

EASI>file = "/demo/map100.pix"
EASI>dbic=1,2,3
EASI>run genhash                      ! Generate image hash
EASI>dbic =
EASI>run genhash                      ! Generate projection hash