JPS6444825A - Brightness measuring method of illuminant - Google Patents

Abstract

PURPOSE:To obtain stable data of the brightness of an illuminant even when the position of the illuminant relative to an optical sensor is changed, by obtaining the average value of the brightness data of lighted parts of the illuminant from the brightness data of a straight line passing central coordinates of the lighted parts of each of many lines which are obtained by extracting the data of the many lines parallel to each other and passing the segment of the illuminant. CONSTITUTION:An illuminant 9 is photographed by a television camera 11. An output signal of the television camera 11 is converted by an A/D converter 12 and taken into a memory 13. Then, corresponding values of the memory 13 are read out onto lines 16-20 parallel to each other and crossing a light emitting member 15 which corresponds to an image of the illuminant 9. Central coordinates 21-23 of the lines 16-20 are calculated from the data of lighted parts among the read-out data. Moreover, corresponding values of the memory 13 are read out onto a line 24 passing the center of each lines. The average value of the data of the lighted parts extracted from the data read out on the straight line 24 is determined to be the brightness of a segment of the illuminant 9. Therefore, even when the relative position of the light emitting member with respect to the optical sensor is changed, the central line of the segment of the illuminant 9 is decided at the same position at all times. Consequently, the brightness data which is stable in spite of positional change of the illuminant with respect to the optical sensor can be obtained.