Estimate the orientation of regions (letters).
The operator estimate_orientation estimates the orientation of regions regarding the "horizontal". The result is returned in degrees. The operator estimate_orientation is used as preparation for character recognition. Lines of letters which deviate slightly (few degrees) from the horizontal are expected as input. The regions can previously be linked with a horizontal mask to enhance stability.
The procedure is based on the Hough Transformation, by which the dominant orientation in the Hough space is determined. The error is at approx. 0.5 degrees.
Regions (input_object) |
region(-array) -> object |
Region(s) to be examined. |
Phi (output_control) |
real(-array) -> real |
Orientation of the regions in degrees. | |
Assertion: (0 <= Phi) && (Phi < 180) |
The operator estimate_orientation returns the value TRUE if the input is not empty. The behavior in case of empty input (no input regions available) is set via the operator set_system(::'no_object_result',<Result>:), the behavior in case of empty region is set via set_system(::'empty_region_result',<Result>:). If necessary an exception is raised.
threshold__, regiongrowing__, connection, dilation_rectangle1