Opencv cvAdaptiveThreshold 函数

最新推荐文章于 2021-12-04 09:49:41 发布

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本文介绍了OpenCV中固定阈值处理与自适应阈值处理的基本概念及使用方法。固定阈值处理是一种基本操作，常用于轮廓检索前的预处理。自适应阈值处理则适用于背景光照变化的情况，通过调整局部阈值来实现更好的效果。

/* Types of thresholding */
#define CV_THRESH_BINARY      0  /* value = value > threshold ? max_value : 0       */
#define CV_THRESH_BINARY_INV  1  /* value = value > threshold ? 0 : max_value       */
#define CV_THRESH_TRUNC       2  /* value = value > threshold ? threshold : value   */
#define CV_THRESH_TOZERO      3  /* value = value > threshold ? value : 0           */
#define CV_THRESH_TOZERO_INV  4  /* value = value > threshold ? 0 : value           */
#define CV_THRESH_MASK        7

#define CV_THRESH_OTSU        8  /* use Otsu algorithm to choose the optimal threshold value;
                                    combine the flag with one of the above CV_THRESH_* values */

/* Applies fixed-level threshold to grayscale image.
   This is a basic operation applied before retrieving contours */
CVAPI(double)  cvThreshold( const CvArr*  src, CvArr*  dst,
                            double  threshold, double  max_value,
                            int threshold_type );

#define CV_ADAPTIVE_THRESH_MEAN_C  0
#define CV_ADAPTIVE_THRESH_GAUSSIAN_C  1

/* Applies adaptive threshold to grayscale image.
   The two parameters for methods CV_ADAPTIVE_THRESH_MEAN_C and
   CV_ADAPTIVE_THRESH_GAUSSIAN_C are:
   neighborhood size (3, 5, 7 etc.),
   and a constant subtracted from mean (...,-3,-2,-1,0,1,2,3,...) */
CVAPI(void)  cvAdaptiveThreshold( const CvArr* src, CvArr* dst, double max_value,
                                  int adaptive_method CV_DEFAULT(CV_ADAPTIVE_THRESH_MEAN_C),
                                  int threshold_type CV_DEFAULT(CV_THRESH_BINARY),
                                  int block_size CV_DEFAULT(3),
                                  double param1 CV_DEFAULT(5));

opencv 调用如下：

cvAdaptiveThreshold( s, dst, 255, CV_ADAPTIVE_THRESH_GAUSSIAN_C,  CV_THRESH_BINARY_INV,  5, 15 );

s:输入单通道数据

dst :输出单通道数据

block_size CV_Assert( blockSize % 2 == 1 && blockSize > 1 ) 为奇数为邻域大小

param1 加权平均减去的值