get_grayval_interpolated — Return gray values of an image at the positions given by tuples of
rows and columns.
get_grayval_interpolated(Image : : Row, Column, Interpolation : Grayval)
The operator get_grayval_interpolated returns interpolated
gray values at several subpixel positions of an Image. The
coordinates of the row positions are given in the tuple
Row, the coordinates of column positions are given in the
tuple Column. The gray values are returned in
Grayval as a tuple of floating point numbers.
The interpolation method can be selected via the parameter
Interpolation. The following interpolation methods are
supported:
The parameter
Grayval is computed using a bilinear interpolation of the
four neighboring gray values of the selected coordinates. Note:
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.
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.
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_interpolated 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.
Image (input_object) singlechannelimage → object (byte / direction / cyclic / int1 / int2 / uint2 / int4 / real / complex)
Image whose gray values are to be accessed.
Row (input_control) point.y(-array) → (real / integer)
Row coordinates of positions.
Default value: 0
Suggested values: 0, 64, 128, 256, 512, 1024
Typical range of values: -0.5
≤
Row
Restriction: -0.5 <= Row && Row < height(Image) - 0.5
Column (input_control) point.x(-array) → (real / integer)
Column coordinates of positions.
Number of elements: Column == Row
Default value: 0
Suggested values: 0, 64, 128, 256, 512, 1024
Typical range of values: -0.5
≤
Column
Restriction: -0.5 <= Column && Column < width(Image) - 0.5
Interpolation (input_control) string → (string)
Interpolation method.
Default value: 'bilinear'
List of values: 'bicubic', 'bicubic_clipped', 'bilinear'
Grayval (output_control) grayval(-array) → (real)
Gray values of the selected image coordinates.
If the parameters are valid, the operator
get_grayval_interpolated returns the value 2 (H_MSG_TRUE). If
necessary, an exception is raised.
get_grayval_contour_xld,
get_grayval
Foundation