measure_projection — Extract a gray value profile perpendicular to a rectangle or annular arc.
measure_projection extracts a one-dimensional gray value profile perpendicular to a rectangle or annular arc. This is done by averaging the gray values in “slices” perpendicular to the major axis of the rectangle or arc. The sampling is done at subpixel positions in the image Image at integer row and column distances (in the coordinate frame of the rectangle) from the center of the rectangle. Since this involves some calculations which can be used repeatedly in several projections, the operator gen_measure_rectangle2 is used to perform these calculations only once, thus increasing the speed of measure_projection significantly. Since there is a trade-off between accuracy and speed in the subpixel calculations of the gray values, different interpolation schemes can be selected in gen_measure_rectangle2 (the interpolation only influences rectangles not aligned with the image axes). The measure object generated with gen_measure_rectangle2 is passed in MeasureHandle.
It should be kept in mind that measure_projection ignores the domain of Image for efficiency reasons. If certain regions in the image should be excluded from the measurement a new measure object with appropriately modified parameters should be generated.
Measure object handle.
Gray value profile.
If the parameter values are correct the operator measure_projection returns the value 2 (H_MSG_TRUE). Otherwise an exception is raised.