| US 7,574,046 B2 | ||
| Optimized lighting method for slider serial reading using class variance | ||
| Yohtaroh Ichimura, Kanagawa (Japan); Shinichi Iwasa, Kanagawa (Japan); Takayuki Erikawa, Kanagawa (Japan); and Yukihiro Nakamura, Kanagawa (Japan) | ||
| Assigned to Hitachi Global Storage Technologies Netherlands B.V., Amsterdam (Netherlands) | ||
| Filed on Dec. 15, 2005, as Appl. No. 11/303,784. | ||
| Claims priority of application No. 2004-362828 (JP), filed on Dec. 15, 2004. | ||
| Prior Publication US 2006/0126934 A1, Jun. 15, 2006 | ||
| Int. Cl. G06K 9/00 (2006.01) | ||
| U.S. Cl. 382—181 | 20 Claims |
| 1. A method for setting a parameter of a light source which applies an image pickup beam to an object surface including a
background and an identification mark, said method comprising:
setting a parameter of the light source which has influence on the brightness of the object surface, to a predetermined value;
generating a grayscale image from the reflection of incident light which is applied to the object surface from the light source
for which said parameter has been set to the predetermined value;
a peak inter-class variance value selecting step which includes setting plural thresholds each for binarizing the grayscale
image in density, calculating inter-class variance values to be produced respectively according to the plural thresholds,
and selecting the largest inter-class variance value as the peak inter-class variance value from the inter-class variance
values calculated;
a maximum inter-class variance value selecting step which includes changing said light source parameter to a plurality of
different values, obtaining peak inter-class variance values respectively for the plurality of different values, and selecting
the largest peak inter-class variance value as the maximum inter-class variance value from the peak inter-class variance values
obtained; and
setting said light source parameter to a value which would give the maximum inter-class variance value.
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