CHAPTER 9 IMAGE ARITHMETIC
9.1 INTRODUCTION
Most image arithmetic may be conveniently performed by
option AR which calls the subroutine ARITHMETIC. This subroutine
accepts as input an arithmetic expression, parses it and applies
it to a set of input maps, leaving the result in a set of output
maps. Because of the considerable power of the program, the
possibility of the user corrupting or deleting data exists.
Please exercise care in using this option; check your expressions
carefully before pressing RETURN.
9.2 INVOKING "ARITHMETIC" FROM MIIPS
After entering MIIPS, enter the two letter option for
ARITHMETIC, "AR". The program then prompts the user to enter an
arithmetic expression:
Enter the expression to be evaluated:
EXPRESSION=
A at this stage will cause ARITHMETIC to exit back to
MIIPS. ARITHMETIC will attempt to parse any other string of
characters which is entered. If a new output file is being
created and the size is not inferred from one or more files on
the right hand side of the equals sign, ARITHMETIC will prompt
the user for a choice of data types for the new expression.
Enter the data format for the new file: (I2, R4 (default),
R8, or C8)
FORMAT=
Having completed the evaluation of the expression, ARITHMETIC
asks if you want to go around again to evaluate another
expression , or exit back to MIIPS.
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9.3 GENERAL FORMAT OF EXPRESSIONS
Expressions accepted by ARITHMETIC are of the form:
Output