topographic_sketchtopographic_sketchtopographic_sketchTopographicSketchTopographicSketch (Operator)

Name

topographic_sketchtopographic_sketchtopographic_sketchTopographicSketchTopographicSketch — Compute the topographic primal sketch of an image.

Signature

Description

topographic_sketchtopographic_sketchtopographic_sketchTopographicSketchTopographicSketch computes the topographic primal sketch of the input image ImageImageImageImageimage. This is done by approximating the image locally by a bicubic polynomial (“facet model”). It serves to calculate the first and second partial derivatives of the image, and thus to classify the image into 11 classes. These classes are coded in the output image SketchSketchSketchSketchsketch as numbers from 1 to 11. The classes are as follows:

Peak                  1
Pit                   2
Ridge                 3
Ravine                4
Saddle                5
Flat                  6
Hillside Slope        7
Hillside Convex       8
Hillside Concave      9
Hillside Saddle      10
Hillside Inflection  11

In order to obtain the separate classes as regions, a threshold operation has to be applied to the result image with the appropriate thresholds.

Parallelization

• Multithreading type: reentrant (runs in parallel with non-exclusive operators).
• Multithreading scope: global (may be called from any thread).
• Automatically parallelized on tuple level.
• Automatically parallelized on channel level.

Parameters

* To extract the Ridges from a Image
read_image(Image,'sinus')
topographic_sketch(Image,Sketch)
threshold(Sketch,Ridges,3,3)

/* To extract the Ridges from a Image */
read_image(&Image,"sinus");
topographic_sketch(Image,&Sketch);
threshold(Sketch,&Ridges,3.0,3.0);

* To extract the Ridges from a Image
read_image(Image,'sinus')
topographic_sketch(Image,Sketch)
threshold(Sketch,Ridges,3,3)

* To extract the Ridges from a Image
read_image(Image,'sinus')
topographic_sketch(Image,Sketch)
threshold(Sketch,Ridges,3,3)

* To extract the Ridges from a Image
read_image(Image,'sinus')
topographic_sketch(Image,Sketch)
threshold(Sketch,Ridges,3,3)

Complexity

Let n be the number of pixels in the image. Then O(n) operations are performed.

Result

topographic_sketchtopographic_sketchtopographic_sketchTopographicSketchTopographicSketch returns 2 (H_MSG_TRUE) if all parameters are correct. If the input is empty the behavior can be set via set_system('no_object_result',<Result>)set_system("no_object_result",<Result>)set_system("no_object_result",<Result>)SetSystem("no_object_result",<Result>)SetSystem("no_object_result",<Result>). If necessary, an exception is raised.

Possible Successors

thresholdthresholdthresholdThresholdThreshold

References

R. Haralick, L. Shapiro: “Computer and Robot Vision, Volume I”; Reading, Massachusetts, Addison-Wesley; 1992; Kapitel 8.13.

Module

Foundation