gen_grid_region

gen_grid_region ( : RegionGrid : RowSteps, ColumnSteps, Type, Width, Height : )

Create a region from lines or pixels.

The operator gen_grid_region creates a grid constructed of lines (Type = 'lines') or pixels (Type = 'points'). In case of 'lines' continuous lines are returned, in case of 'points' only the intersections of the lines. Starting from the pixel (0,0) to the pixel (Height-1,Width-1) the grid is built up at stepping width RowSteps in line direction and ColumnSteps in column direction. In the 'lines' mode RowSteps, ColumnSteps respectively, can be set to zero. In this case only columns, lines respectively, are created.

Attention

If a very small pattern is chosen (RowSteps < 4 oder ColumnSteps < 4) the created region requires much storage.

In the 'points' mode RowSteps and ColumnSteps must not be set to zero.

Parameters

`RegionGrid` (output_object)	region `->` object
Created lines/pixel region.

`RowSteps` (input_control)	extent.y `->` integer / real
Step width in line direction or zero.
Default value: 10
Suggested values: 0, 2, 3, 4, 5, 7, 10, 15, 20, 30, 50, 100
Typical range of values: `0 <= RowSteps <= 512` (lin)
Minimum increment: 1
Recommended increment: 10
Restriction: `(RowSteps > 1) \|\| (RowSteps == 0)`

`ColumnSteps` (input_control)	extent.x `->` integer / real
Step width in column direction or zero.
Default value: 10
Suggested values: 0, 2, 3, 4, 5, 7, 10, 15, 20, 30, 50, 100
Typical range of values: `0 <= ColumnSteps <= 512` (lin)
Minimum increment: 1
Recommended increment: 10
Restriction: `(ColumnSteps > 1) \|\| (ColumnSteps == 0)`

`Type` (input_control)	string `->` string
Type of created pattern.
Default value: 'lines'
List of values: 'lines', 'points'

`Width` (input_control)	extent.x `->` integer
Maximum width of pattern.
Default value: 512
Suggested values: 128, 256, 512, 1024
Typical range of values: `1 <= Width <= 1024` (lin)
Minimum increment: 1
Recommended increment: 10
Restriction: `Width >= 1`

`Height` (input_control)	extent.y `->` integer
Maximum height of pattern.
Default value: 512
Suggested values: 128, 256, 512, 1024
Typical range of values: `1 <= Height <= 1024` (lin)
Minimum increment: 1
Recommended increment: 10
Restriction: `Height >= 1`

Example

read_image(Image,'fabrik') 
gen_grid_region(Raster,10,10,'lines',512,512) 
reduce_domain(Image,Raster,Mask) 
sobel_amp(Mask,GridSobel,'sum_abs',3) 
disp_image(GridSobel,WindowHandle).

Complexity

The necessary storage (in bytes) for the region is:

O((ImageWidth / ColumnSteps) * (ImageHeight / RowSteps))

Result

If the parameter values are correct the operator gen_grid_region returns the value 2 (H_MSG_TRUE). Otherwise an exception handling is raised. The clipping according to the current image format is set via the operator set_system('clip_region',<'true'/'false'>).

Parallelization Information

gen_grid_region is reentrant and processed without parallelization.

Possible Successors

reduce_domain, paint_region

Alternatives

gen_region_line, gen_region_polygon, gen_region_points, gen_region_runs

See also

gen_checker_region, reduce_domain

Module

Region processing