thresholdthresholdThresholdThreshold (Operator)

Name

thresholdthresholdThresholdThreshold — Segment an image using global threshold.

Signature

Description

thresholdthresholdThresholdThresholdThreshold selects the pixels from the input image whose gray values g fulfill the following condition:

All points of an image fulfilling the condition are returned as one region. If more than one gray value interval is passed (tuples for MinGrayMinGrayMinGrayMinGrayminGray and MaxGrayMaxGrayMaxGrayMaxGraymaxGray), one separate region is returned for each interval. For vector field images, the threshold is not applied to gray values but to the lengths of the vectors.

Attention

For input images of an integer type, floating point values in MinGrayMinGrayMinGrayMinGrayminGray and MaxGrayMaxGrayMaxGrayMaxGraymaxGray are truncated.

Execution Information

• 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 internal data level.

Parameters

read_image(Image,'fabrik')
sobel_dir(Image,EdgeAmp,EdgeDir,'sum_abs',3)
threshold(EdgeAmp,Seg,50,255)
skeleton(Seg,Rand)
connection(Rand,Lines)
select_shape(Lines,Edges,'area','and',10,1000000)

read_image(&Image,"fabrik");
sobel_amp(Image,&EdgeAmp,"sum_abs",3);
threshold(EdgeAmp,&Seg,50.0,255.0);
skeleton(Seg,&Rand);
connection(Rand,&Lines);
select_shape(Lines,&Edges,"area","and",10.0,1000000.0);

read_image(Image,'fabrik')
sobel_dir(Image,EdgeAmp,EdgeDir,'sum_abs',3)
threshold(EdgeAmp,Seg,50,255)
skeleton(Seg,Rand)
connection(Rand,Lines)
select_shape(Lines,Edges,'area','and',10,1000000)

read_image(Image,'fabrik')
sobel_dir(Image,EdgeAmp,EdgeDir,'sum_abs',3)
threshold(EdgeAmp,Seg,50,255)
skeleton(Seg,Rand)
connection(Rand,Lines)
select_shape(Lines,Edges,'area','and',10,1000000)

read_image(Image,'fabrik')
sobel_dir(Image,EdgeAmp,EdgeDir,'sum_abs',3)
threshold(EdgeAmp,Seg,50,255)
skeleton(Seg,Rand)
connection(Rand,Lines)
select_shape(Lines,Edges,'area','and',10,1000000)

Complexity

Let A be the area of the input region. Then the runtime complexity is O(A).

Result

thresholdthresholdThresholdThresholdThreshold returns 2 (H_MSG_TRUE) if all parameters are correct. The behavior with respect to the input images and output regions can be determined by setting the values of the flags 'no_object_result'"no_object_result""no_object_result""no_object_result""no_object_result", 'empty_region_result'"empty_region_result""empty_region_result""empty_region_result""empty_region_result", and 'store_empty_region'"store_empty_region""store_empty_region""store_empty_region""store_empty_region" with set_systemset_systemSetSystemSetSystemSetSystem. If necessary, an exception is raised.

Possible Predecessors

histo_to_threshhisto_to_threshHistoToThreshHistoToThreshHistoToThresh, min_max_graymin_max_grayMinMaxGrayMinMaxGrayMinMaxGray, sobel_ampsobel_ampSobelAmpSobelAmpSobelAmp, binomial_filterbinomial_filterBinomialFilterBinomialFilterBinomialFilter, gauss_filtergauss_filterGaussFilterGaussFilterGaussFilter, reduce_domainreduce_domainReduceDomainReduceDomainReduceDomain, fill_interlacefill_interlaceFillInterlaceFillInterlaceFillInterlace

Possible Successors

connectionconnectionConnectionConnectionConnection, dilation1dilation1Dilation1Dilation1Dilation1, erosion1erosion1Erosion1Erosion1Erosion1, openingopeningOpeningOpeningOpening, closingclosingClosingClosingClosing, rank_regionrank_regionRankRegionRankRegionRankRegion, shape_transshape_transShapeTransShapeTransShapeTrans, skeletonskeletonSkeletonSkeletonSkeleton

Alternatives

class_2dim_supclass_2dim_supClass2dimSupClass2dimSupClass2dimSup, hysteresis_thresholdhysteresis_thresholdHysteresisThresholdHysteresisThresholdHysteresisThreshold, dyn_thresholddyn_thresholdDynThresholdDynThresholdDynThreshold, binary_thresholdbinary_thresholdBinaryThresholdBinaryThresholdBinaryThreshold, char_thresholdchar_thresholdCharThresholdCharThresholdCharThreshold, auto_thresholdauto_thresholdAutoThresholdAutoThresholdAutoThreshold, dual_thresholddual_thresholdDualThresholdDualThresholdDualThreshold

See also

zero_crossingzero_crossingZeroCrossingZeroCrossingZeroCrossing, background_segbackground_segBackgroundSegBackgroundSegBackgroundSeg, regiongrowingregiongrowingRegiongrowingRegiongrowingRegiongrowing

Module

Foundation