get_grayval_contour_xld — Return gray values of an image at the positions of an XLD contour.
get_grayval_contour_xld(Image, Contour : : Interpolation : Grayval)
The operator get_grayval_contour_xld returns interpolated
gray values at several subpixel positions of the Image.
The coordinates of the positions are specified via one XLD contour
Contour. The gray values are returned in Grayval.
The interpolation method can be selected via the parameter
Interpolation:
The results are
the gray values of the nearest pixels to the selected coordinates.
For images of type byte, direction, cyclic, uint2, int1, int2,
int4, and int8, the parameter Grayval is a tuple of
integer numbers. For images of type real and complex, the
parameter Grayval is a tuple of floating point numbers.
The parameter
Grayval is computed using a bilinear interpolation of the
four neighboring gray values of the selected coordinates. The
result is a tuple of floating point numbers. The runtime
increases significantly compared to 'nearest_neighbor'.
Direction and cyclic images are treated like byte images.
The parameter
Grayval is computed using a bicubic interpolation of
sixteen neighboring gray values of the selected coordinates. The
result is a tuple of floating point numbers. The runtime
increases significantly compared to 'bilinear'.
Direction and cyclic images are treated like byte images. In this
mode, the resulting gray values may contain values that lie
outside of the range of numbers that can be represented by the
input image type.
The parameter
Grayval is computed using a bicubic interpolation of
sixteen neighboring gray values of the selected coordinates. The
result is a tuple of floating point numbers. The runtime
increases significantly compared to 'bilinear'.
Direction and cyclic images are treated like byte images. In this
mode, resulting gray values that lie outside of the range of
numbers that can be represented by the input image type are
clipped to that range.
Note that get_grayval_contour_xld does not take the domain of
the image into account, i.e., if the domain has been reduced, e.g.,
with reduce_domain, gray values are returned even for points
that lie outside the domain.
Please note also that each point of the XLD contour must be in the
range -0.5 <= row coordinate <
height(Image)-0.5 and -0.5 <= column
coordinate < width(Image)-0.5.
Image (input_object) singlechannelimage → object (byte / direction / cyclic / int1 / int2 / uint2 / int4 / real / complex)
Image whose gray values are to be accessed.
Contour (input_object) xld_cont → object
Input XLD contour with the coordinates of the positions.
Interpolation (input_control) string → (string)
Interpolation method.
Default value: 'nearest_neighbor'
List of values: 'bicubic', 'bicubic_clipped', 'bilinear', 'nearest_neighbor'
Grayval (output_control) grayval(-array) → (real / integer)
Gray values of the selected image coordinates.
If the parameters are valid, the operator
get_grayval_contour_xld returns the value TRUE. If
necessary, an exception is raised.
read_image,
draw_xld,
gen_contour_polygon_xld,
edges_sub_pix
Foundation