get_grayvalT_get_grayvalGetGrayvalGetGrayval (Operator)


get_grayvalT_get_grayvalGetGrayvalGetGrayval — Access the gray values of an image object.


get_grayval(Image : : Row, Column : Grayval)

Herror T_get_grayval(const Hobject Image, const Htuple Row, const Htuple Column, Htuple* Grayval)

void GetGrayval(const HObject& Image, const HTuple& Row, const HTuple& Column, HTuple* Grayval)

HTuple HImage::GetGrayval(const HTuple& Row, const HTuple& Column) const

HTuple HImage::GetGrayval(Hlong Row, Hlong Column) const

static void HOperatorSet.GetGrayval(HObject image, HTuple row, HTuple column, out HTuple grayval)

HTuple HImage.GetGrayval(HTuple row, HTuple column)

HTuple HImage.GetGrayval(int row, int column)


The parameter GrayvalGrayvalGrayvalGrayvalgrayval is a tuple of floating point numbers or integer numbers which returns the gray values of several pixels of ImageImageImageImageimage. For a multi-channel image, a group of elements, in particular one value for each channel (or two values for each channel for complex or vector field images), is returned for each pixel. The row coordinates of the pixels are specified in the tuple RowRowRowRowrow, the column coordinates are specified in the tuple ColumnColumnColumnColumncolumn.

Note that get_grayvalget_grayvalGetGrayvalGetGrayvalGetGrayval does not take the domain of the image into account, i.e., if the domain has been reduced, e.g., with reduce_domainreduce_domainReduceDomainReduceDomainReduceDomain, gray values are returned even for points that lie outside the domain.


The type of the values of GrayvalGrayvalGrayvalGrayvalgrayval depends on the type of the gray values of the channels of the image ImageImageImageImageimage. The operator get_grayvalget_grayvalGetGrayvalGetGrayvalGetGrayval produces quite some overhead. Typically, it is used to get single gray values of an image (e.g., get_mpositionget_mpositionGetMpositionGetMpositionGetMposition followed by get_grayvalget_grayvalGetGrayvalGetGrayvalGetGrayval). It is not suitable for programming image processing operations such as filters. In this case it is more useful to use the operator get_image_pointer1get_image_pointer1GetImagePointer1GetImagePointer1GetImagePointer1 and to directly use the C or C++ interface for integrating own procedures.

Execution Information


ImageImageImageImageimage (input_object)  (multichannel-)image objectHImageHImageHobject (byte / direction / cyclic / int1 / int2 / uint2 / int4 / int8 / real / complex / vector_field)

Image whose gray value is to be accessed.

RowRowRowRowrow (input_control)  point.y(-array) HTupleHTupleHtuple (integer) (int / long) (Hlong) (Hlong)

Row coordinates of pixels to be viewed.

Default value: 0

Suggested values: 0, 64, 128, 256, 512, 1024

Typical range of values: 0 ≤ Row Row Row Row row ≤ 32768 (lin)

Minimum increment: 1

Recommended increment: 1

Restriction: 0 <= Row && Row < height(Image)

ColumnColumnColumnColumncolumn (input_control)  point.x(-array) HTupleHTupleHtuple (integer) (int / long) (Hlong) (Hlong)

Column coordinates of pixels to be viewed.

Number of elements: Column == Row

Default value: 0

Suggested values: 0, 64, 128, 256, 512, 1024

Typical range of values: 0 ≤ Column Column Column Column column ≤ 32768 (lin)

Minimum increment: 1

Recommended increment: 1

Restriction: 0 <= Column && Column < width(Image)

GrayvalGrayvalGrayvalGrayvalgrayval (output_control)  grayval-array HTupleHTupleHtuple (real / integer) (double / int / long) (double / Hlong) (double / Hlong)

Gray values of indicated pixels.


If the state of the parameters is correct, the operator get_grayvalget_grayvalGetGrayvalGetGrayvalGetGrayval returns the value 2 (H_MSG_TRUE). The behavior in case of empty input (no input images available) is set via the operator set_system('no_object_result',<Result>)set_system("no_object_result",<Result>)SetSystem("no_object_result",<Result>)SetSystem("no_object_result",<Result>)SetSystem("no_object_result",<Result>). If necessary, an exception is raised.

Possible Predecessors



get_image_pointer1get_image_pointer1GetImagePointer1GetImagePointer1GetImagePointer1, get_grayval_interpolatedget_grayval_interpolatedGetGrayvalInterpolatedGetGrayvalInterpolatedGetGrayvalInterpolated, get_grayval_contour_xldget_grayval_contour_xldGetGrayvalContourXldGetGrayvalContourXldGetGrayvalContourXld

See also