| 摘要 |
PURPOSE:To detect the visual range of daytime by finding out visibility distance based upon the ratio of brightness values of two recognition plates drawn by white and black. CONSTITUTION:Image information including two recognition plates 12, 13 drawn by white and black is stored in a multi-level image memory 33 through a television camera 31 (11) and an A/D converter 32. As to the recognition plates 12, 13, the size of the plate 13 is larger than that of the plate 12 so that the number of picture elements on a screen is identical in both the plates 12, 13. A brightness ratio calculating part 34 segments the areas of the plates 12, 13 from the memory 33 and finds out the brightness ratio of white and black parts in respective plates 12, 13. A visibility distance calculation part 35 finds out a visibility distance from the brightness ratio of the two plates 12, 13 and the set interval between the plates 12, 13. When the output of the calculation part 35 is shorter than a previously set visibility distance, a visual range validity deciding part 36 outputs an invalid visual range decision to the post stage, while outputting a valid visual range decision in the other case. |
