BITHASH

Description

BITHASH computes a hash number that represents a window of bitmap values from an input bitmap segment. This hash number is used as a checksum for software testing.

Parameters

bithash(file, dbib, dbiw)

Name	Type	Caption	Length	Value range
FILE *	str	Input file name	1 -
DBIB *	List[int]	Input bitmap channel(s)	1 -
DBIW	List[int]	Raster input window	0 - 4	Xoffset, Yoffset, Xsize, Ysize

* Required parameter

Parameter descriptions

FILE

Specifies the name of the GDB-supported file containing the bitmap data for which the hash number will be computed.

DBIB

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

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.

Return Value

Returns: Image Statistics

Type:  PCI_FLOAT

Parameter: imstat

Upon completion, BITHASH writes out to the IMSTAT parameter a hash number for each of the bitmap segments sampled. This hash number is always a number between 0 and 32767.

Details

BITHASH computes a hash value for a window of bitmap data in a GDB-supported file. This function is primarily used for the construction of test procedures.

The hash function results in a value between 0 and 32767 being placed into the IMSTAT parameter.

Example

Compute and display the hash values for each of the bitmaps in irvine.pix.

from pci.bithash import bithash

file = 'irvine.pix'        #irvine.pix in the program's working dir
dbib = [9,10,11,12,13,14,15,16]
dbiw = []                  #defaults to whole image

bithash(file,dbib,dbiw)