select_characters

    scale_image_max (TmpObj_MonoReduced_OCR_02_0, ImageScaleMax1)
    invert_image (ImageScaleMax1, ImageInvert)
    binary_threshold (ImageInvert, Region, 'max_separability', 'light', UsedThreshold)
    connection (Region, ConnectedRegions2)
    opening_rectangle1 (ConnectedRegions2, RegionOpening, 3,3)
    select_characters (ConnectedRegions2, SelectedRegions1, 'false', 'medium', 25, 36, 'false', 'false', 'none', 'false', 'medium', 'false', 0, 'completion')

*     select_shape (RegionOpening, SelectedRegions, 'width', 'and', 5, 45)
*     select_shape (SelectedRegions, SelectedRegions1, 'height', 'and', 5, 56)

直接做字符检测：select_characters