org.opencv.features2d

Class SimpleBlobDetector

java.lang.Object

org.opencv.core.Algorithm

org.opencv.features2d.Feature2D

org.opencv.features2d.SimpleBlobDetector

public class SimpleBlobDetector
extends Feature2D

Class for extracting blobs from an image. : The class implements a simple algorithm for extracting blobs from an image: 1. Convert the source image to binary images by applying thresholding with several thresholds from minThreshold (inclusive) to maxThreshold (exclusive) with distance thresholdStep between neighboring thresholds. 2. Extract connected components from every binary image by findContours and calculate their centers. 3. Group centers from several binary images by their coordinates. Close centers form one group that corresponds to one blob, which is controlled by the minDistBetweenBlobs parameter. 4. From the groups, estimate final centers of blobs and their radiuses and return as locations and sizes of keypoints. This class performs several filtrations of returned blobs. You should set filterBy\* to true/false to turn on/off corresponding filtration. Available filtrations:

• By color. This filter compares the intensity of a binary image at the center of a blob to blobColor. If they differ, the blob is filtered out. Use blobColor = 0 to extract dark blobs and blobColor = 255 to extract light blobs.
• By area. Extracted blobs have an area between minArea (inclusive) and maxArea (exclusive).
• By circularity. Extracted blobs have circularity (\(\frac{4*\pi*Area}{perimeter * perimeter}\)) between minCircularity (inclusive) and maxCircularity (exclusive).
• By ratio of the minimum inertia to maximum inertia. Extracted blobs have this ratio between minInertiaRatio (inclusive) and maxInertiaRatio (exclusive).
• By convexity. Extracted blobs have convexity (area / area of blob convex hull) between minConvexity (inclusive) and maxConvexity (exclusive).

Default values of parameters are tuned to extract dark circular blobs.

Method Summary

Modifier and Type	Method and Description
static SimpleBlobDetector	__fromPtr__(long addr)
static SimpleBlobDetector	create()
static SimpleBlobDetector	create(SimpleBlobDetector_Params parameters)
java.util.List<MatOfPoint>	getBlobContours()
java.lang.String	getDefaultName() Returns the algorithm string identifier.
SimpleBlobDetector_Params	getParams()
void	setParams(SimpleBlobDetector_Params params)

Methods inherited from class org.opencv.features2d.Feature2D

compute, compute, defaultNorm, descriptorSize, descriptorType, detect, detect, detect, detect, detectAndCompute, detectAndCompute, empty, read, write

Methods inherited from class org.opencv.core.Algorithm

clear, getNativeObjAddr, save

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

__fromPtr__

public static SimpleBlobDetector __fromPtr__(long addr)

create

public static SimpleBlobDetector create()

create

public static SimpleBlobDetector create(SimpleBlobDetector_Params parameters)

getBlobContours

public java.util.List<MatOfPoint> getBlobContours()

getDefaultName

public java.lang.String getDefaultName()

Description copied from class: Algorithm

Returns the algorithm string identifier. This string is used as top level xml/yml node tag when the object is saved to a file or string.

Overrides:

getDefaultName in class Feature2D

Returns:

automatically generated

getParams

public SimpleBlobDetector_Params getParams()

setParams

public void setParams(SimpleBlobDetector_Params params)