OpenCV中cvThreshold/threshold返回的double是什麼？

Question

我寫在OpenCV中的Android應用程序，並已花了幾個小時尋找到在C例如http://www.shervinemami.info/blobs.html

常用的幾個功能的cvThreshold功能的示例程序使用像這樣 -

cvThreshold(planeH, planeH, 18, UCHAR_MAX, CV_THRESH_BINARY_INV); 
cvThreshold(planeS, planeS, 50, UCHAR_MAX, CV_THRESH_BINARY); 
cvThreshold(planeV, planeV, 80, UCHAR_MAX, CV_THRESH_BINARY); 

帶有5個參數。文檔我發現該函數顯示相同的參數，但該函數似乎返回一個雙精度而不是無效。

的參數是 -

cvThreshold(sourceImage, destinationImage, minThreshold, maxThreshold, 
      thresholdType); 

據我可以告訴（並且被記錄），基於該函數檢查源圖像以查看哪些元素落在指定的範圍內（最小值和最大值的閾值之間）在選定的閾值類型上，並將結果輸出到目標圖像。但是我不知道爲什麼會返回一個雙 ...

提供了Android版本的文檔包含下面。

/** 
* Applies a fixed-level threshold to each array element. 
* 
* The function applies fixed-level thresholding to a single-channel array. The 
* function is typically used to get a bi-level (binary) image out of a 
* grayscale image ("compare" could be also used for this purpose) or for 
* removing a noise, that is, filtering out pixels with too small or too large 
* values. There are several types of thresholding supported by the function. 
* They are determined by "thresholdType" : 
* * THRESH_BINARY 
* 
* dst(x,y) = maxVal if src(x,y) > thresh; 0 otherwise 
* 
* * THRESH_BINARY_INV 
* 
* dst(x,y) = 0 if src(x,y) > thresh; maxVal otherwise 
* 
* * THRESH_TRUNC 
* 
* dst(x,y) = threshold if src(x,y) > thresh; src(x,y) otherwise 
* 
* * THRESH_TOZERO 
* 
* dst(x,y) = src(x,y) if src(x,y) > thresh; 0 otherwise 
* 
* * THRESH_TOZERO_INV 
* 
* dst(x,y) = 0 if src(x,y) > thresh; src(x,y) otherwise 
* 
* Also, the special value "THRESH_OTSU" may be combined with one of the above 
* values. In this case, the function determines the optimal threshold value 
* using the Otsu's algorithm and uses it instead of the specified "thresh". 
* The function returns the computed threshold value. 
* Currently, the Otsu's method is implemented only for 8-bit images. 
* 
* @param src Source array (single-channel, 8-bit of 32-bit floating point). 
* @param dst Destination array of the same size and type as "src". 
* @param thresh Threshold value. 
* @param maxval a maxval 
* @param type a type 
* 
* @see <a href="http://opencv.itseez.com/modules/imgproc/doc/miscellaneous_transformations.html#threshold">org.opencv.imgproc.Imgproc.threshold</a> 
* @see org.opencv.imgproc.Imgproc.findContours 
* @see org.opencv.core.Core.max 
* @see org.opencv.imgproc.Imgproc.adaptiveThreshold 
* @see org.opencv.core.Core.compare 
* @see org.opencv.core.Core.min 
*/ 

Answer 1

它是使用Otsu's method