Access the gray values of an image object.
The operator Grayval is a tuple of floating point numbers, integer respectively, which returns the gray values of several pixels of Image. The line coordinates of the pixels are in the tuple Row, the columns in Column.
The type of the values of Grayval depends on the type of the gray values.
Gray values which do not belong to the image can also be accessed. The state of these gray values is not ascertained.
The operator get_grayval involves a lot of work. It is not suitable for programming image processing operations such as filters. In this case it is more useful to use the procedure get_image_pointer1 or to directly use the C interface for integrating own procedures.
|
Image (input_object) |
image -> object : byte / direction / cyclic / int1 / int2 / uint2 / int4 / real / complex |
| Image whose gray value is to be accessed. | |
|
Row (input_control) |
point.y(-array) -> integer |
| Line numbers of pixels to be viewed. | |
| Default value: 0 | |
| Suggested values: 0, 64, 128, 256, 512, 1024 | |
| Typical range of values: 0 <= Row <= 32768 (lin) | |
| Minimum increment: 1 | |
|
Recommended increment: 1 | |
| Restriction: (0 <= Row) && (Row < height(Image)) | |
|
Column (input_control) |
point.x(-array) -> integer |
| Column numbers of pixels to be viewed. | |
| Default value: 0 | |
| Suggested values: 0, 64, 128, 256, 512, 1024 | |
| Typical range of values: 0 <= Column <= 32768 (lin) | |
| Minimum increment: 1 | |
|
Recommended increment: 1 | |
| Number of elements: Column == Row | |
| Restriction: (0 <= Column) && (Column < width(Image)) | |
|
Grayval (output_control) |
grayval(-array) -> real / integer |
| Gray values of indicated pixels. | |
| Number of elements: Grayval == Row | |
If the state of the parameters is correct the operator get_grayval 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>). If necessary an exception handling is raised.
get_grayval is reentrant and processed without parallelization.
Image / region / XLD management
