Omron F250-UME Software Manual page 992

Terminology
7-4 Terminology
HELP
Term
Binary Binary refers to the separation of the density images with 256 gradations read by the Cam-
era into black pixels and white pixels. Upper and lower threshold values (binary levels) are
set and the parts of the density image that fall within that gradatiion range are converted to
white pixels and the rest are converted to black pixels. The Controller uses the white pixels
to measure the object.
Density image
2's complement A common method used to express negative numbers in binary format. The 2's comple-
ment method expresses a negative number by inverting all of the bits of the positive value
and then adding 1.
Example: The 2's complement of
−)
There is an easy way to calculate a 2's complement without doing the above calculation,
that is, you invert all of the bits of the positive value and then add 1.
00000001
11111110
11111111
The MSB can be used to determine if a number is positive or negative.
If the MSB is 0, the number is positive (or zero).
If the MSB is 1, the number is negative.
Numbers expressed in the 2's complement method are convenient in that they can be
used in calculations without further conversion.
Example for
+)
7-(12)
This section explains terms listed beside the HELP icons. Terms explained in
the main body of the manual are not listed here.
Binary level
Binary image
Upper
Lower
-
The value 1 can be derived from 0
-
Subtract 1 from 0 assuming there is a 1 in this place.
00000000 (= 0)
00000001 (= 1)
11111111 (=-1)
The 2's complement of
(= 1)
Invert all bits.
Add 1.
(=-1)
-
1 + 10 = 9:
11111111 (= -1)
00001010 (= 10)
00001001 (= 9)
Explanation
-
1 is expressed as follows:
-
1.
-
1 (in 8 digits)
Section 7-4