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User Manual SIPLACE 80S-20/F4 6 Vision functions Software version SR.406.xx 02/2000 Issue US 6.5 Teach Fiducial 253 6.5.5 Contrast Sensitivity Menu The Contrast sensitivity men u provid es options for optimiz ing the co …
6 Vision functions User Manual SIPLACE 80S-20/F4
6.5 Teach Fiducial Software version SR.406.xx 02/2000 Issue US
252
The uniqueness value appears as the measurement results. This may vary between 0 (= unsat-
isfactory) and 100 (= very good) differentiation capability. 6
Practice shows that a uniqueness value of at least 60 must be achieved for fiducials and ink dots. 6
Å Repeat the teaching process a number of times with changed field sizes. In this way you can
optimize the uniqueness value.
Å Press Esc to quit this option.
NOTE 6
If you wish to use a fiducial despite the fact that it has a low uniqueness value, you should
ensure that the fiducial has a good quality value (see Section 6.5.6.2 on page 263).
If the quality is bad as well, it would be better to select another fiducial (see Criteria for Cre-
ating Fiducials in Section 6.2.5 on page 216). 6
User Manual SIPLACE 80S-20/F4 6 Vision functions
Software version SR.406.xx 02/2000 Issue US 6.5 Teach Fiducial
253
6.5.5 Contrast Sensitivity Menu
The Contrast sensitivity menu provides options for optimizing the contrast between the fiducial
and its surroundings. 6
NOTE 6
All of the options in this menu are only accessible if you have loaded a fiducial beforehand. If you
have done so, this will be indicated by the text on the button being black (rather than grayed out).
The fiducial number and fiducial name are displayed in the Fiducial display field.
If you have not loaded a fiducial you will only be able to select the ’Program Transform 5’ Option.
6
Fig. 6.5 - 17 Contrast sensitivity menu, options
Each pixel of the video camera contains one unit of 8-bit gray-scale information. The significance
of the values is as follows: 6
0 = black and
255 = white
6 Vision functions User Manual SIPLACE 80S-20/F4
6.5 Teach Fiducial Software version SR.406.xx 02/2000 Issue US
254
To make it easier for you to assess the range of brightness or the contrast, these gray-scale values
have been converted with the help of transformation tables into color as is shown below: 6
NOTE 6
In order to achieve a good uniqueness value the contrast difference between the fiducial and its
surroundings should be at least 75. For example, if the background is green the fiducial should
be orange.
If the contrast is unsatisfactory you can select in the menu between five pre-programmed trans-
formation tables in order to obtain a color image which is capable of supplying the necessary in-
formation. In addition, you can also program a transformation table yourself. 6
NOTE 6
When the color presentation is changed the fiducial will be taught at the same time.
Gray scale Allocated color
0black
30 violet
50 blue
77 blue-green
100 green
127 brown
150 red
175 orange
200 yellow
255 white
Tab. 6.5.1