fast_thresholdfast_thresholdFastThresholdFastThresholdfast_threshold（算子）

名称

fast_thresholdfast_thresholdFastThresholdFastThresholdfast_threshold — 使用全局阈值对图像进行快速阈值处理。

签名

fast_threshold(Image : Region : MinGray, MaxGray, MinSize : )

描述

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

To reduce the processing time, the selection is done in two steps: At first, all points lying on selected horizontal lines that are specified by their distance MinSizeMinSizeMinSizeMinSizeminSizemin_size are processed. In the next step the neighborhood (size (2*MinSize+1) x (2*MinSize+1)) of all previously selected points are processed.

注意

On multi-core computers supporting the SSE2 instruction set, thresholdthresholdThresholdThresholdThresholdthreshold is most likely faster than fast_thresholdfast_thresholdFastThresholdFastThresholdFastThresholdfast_threshold. fast_thresholdfast_thresholdFastThresholdFastThresholdFastThresholdfast_threshold may only be preferred to thresholdthresholdThresholdThresholdThresholdthreshold if those features are not available, e.g., on embedded platforms.

执行信息

多线程类型：可重入（与非独占算子并行运行）。
多线程作用域：全局（可从任何线程调用）。
在元组级别上自动并行化。
在内部数据级别上自动并行化。

参数

ImageImageImageImageimageimage (输入对象) singlechannelimage(-array) → object (byte / uint2 / direction / cyclic / real)

输入图像。

RegionRegionRegionRegionregionregion (输出对象) region(-array) → object

分割区域。

MinGrayMinGrayMinGrayMinGrayminGraymin_gray (输入控制) number → (real / integer)

Lower threshold for the gray values.

默认值： 128

建议值： 0.0, 10.0, 30.0, 64.0, 128.0, 200.0, 220.0, 255.0

值范围： 0.0 ≤ MinGray MinGray MinGray MinGray minGray min_gray ≤ 255.0 (lin)

最小增量： 1

建议增量： 5.0

MaxGrayMaxGrayMaxGrayMaxGraymaxGraymax_gray (输入控制) number → (real / integer)

Upper threshold for the gray values.

默认值： 255.0

建议值： 0.0, 10.0, 30.0, 64.0, 128.0, 200.0, 220.0, 255.0

值范围： 0.0 ≤ MaxGray MaxGray MaxGray MaxGray maxGray max_gray ≤ 255.0 (lin)

最小增量： 1

建议增量： 5.0

MinSizeMinSizeMinSizeMinSizeminSizemin_size (输入控制) number → (integer)

Minimum size of objects to be extracted.

默认值： 20

建议值： 5, 10, 15, 20, 25, 30, 40, 50, 60, 70, 100

值范围： 2 ≤ MinSize MinSize MinSize MinSize minSize min_size ≤ 200 (lin)

最小增量： 1

建议增量： 2

复杂度

Let A be the area of the output region and height the height of ImageImageImageImageimageimage. Then the runtime complexity is O(A + height / MinSizeMinSizeMinSizeMinSizeminSizemin_size).

结果

fast_thresholdfast_thresholdFastThresholdFastThresholdFastThresholdfast_threshold 在所有参数正确时返回 2 (H_MSG_TRUE)。通过 set_systemset_systemSetSystemSetSystemSetSystemset_system 算子设置标志 'no_object_result'"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""empty_region_result" 和 'store_empty_region'"store_empty_region""store_empty_region""store_empty_region""store_empty_region""store_empty_region" 的值，可确定系统对输入图像和输出区域的行为方式。如有必要，则抛出异常。

可能的前趋

histo_to_threshhisto_to_threshHistoToThreshHistoToThreshHistoToThreshhisto_to_thresh, min_max_graymin_max_grayMinMaxGrayMinMaxGrayMinMaxGraymin_max_gray, sobel_ampsobel_ampSobelAmpSobelAmpSobelAmpsobel_amp, binomial_filterbinomial_filterBinomialFilterBinomialFilterBinomialFilterbinomial_filter, gauss_filtergauss_filterGaussFilterGaussFilterGaussFiltergauss_filter, reduce_domainreduce_domainReduceDomainReduceDomainReduceDomainreduce_domain, fill_interlacefill_interlaceFillInterlaceFillInterlaceFillInterlacefill_interlace

可能的后继

connectionconnectionConnectionConnectionConnectionconnection, dilation1dilation1Dilation1Dilation1Dilation1dilation1, erosion1erosion1Erosion1Erosion1Erosion1erosion1, openingopeningOpeningOpeningOpeningopening, closingclosingClosingClosingClosingclosing, rank_regionrank_regionRankRegionRankRegionRankRegionrank_region, shape_transshape_transShapeTransShapeTransShapeTransshape_trans, skeletonskeletonSkeletonSkeletonSkeletonskeleton

替代

thresholdthresholdThresholdThresholdThresholdthreshold, gen_grid_regiongen_grid_regionGenGridRegionGenGridRegionGenGridRegiongen_grid_region, dilation_rectangle1dilation_rectangle1DilationRectangle1DilationRectangle1DilationRectangle1dilation_rectangle1, dyn_thresholddyn_thresholdDynThresholdDynThresholdDynThresholddyn_threshold

另见

class_2dim_supclass_2dim_supClass2dimSupClass2dimSupClass2dimSupclass_2dim_sup, hysteresis_thresholdhysteresis_thresholdHysteresisThresholdHysteresisThresholdHysteresisThresholdhysteresis_threshold

模块

基础

算子