WatershedVincentSoille1991 (feature 0.23 API)

java.lang.Object
- boofcv.alg.segmentation.watershed.WatershedVincentSoille1991

Direct Known Subclasses:

WatershedVincentSoille1991.Connect4, WatershedVincentSoille1991.Connect8
```
public abstract class WatershedVincentSoille1991
extends java.lang.Object
```
Fast watershed based upon Vincient and Soille's 1991 paper [1]. Watershed segments an image using the idea of immersion simulation. For example, the image is treated as a topological map and if you let a droplet of water flow down from each pixel the location the droplets cluster in defines a region. Two different methods are provided for processing the image, a new region is created at each local minima or the user provides an initial seed for each region for it to grow from. The output will be a segmented image with watersheds being assign a value of 0 and each region a value > 0. Watersheds are assigned to pixels which are exactly the same distance from multiple regions, thus it is ambiguous which one it is a member of.

If the image is processed with process(GrayU8) then a new region is created at each local minima and assigned a unique ID > 0. The total number of regions found is returned by getTotalRegions(). This technique will lead to over segmentation on many images.

Initial seeds are provided with a call to process(GrayU8, GrayS32). No new regions will be created. By providing an initial set of seeds over segmentation can be avoided, but prior knowledge of the image is typically needed to create the seeds.

NOTES:
- For faster processing, the internal labeled image has a 1 pixel border around it. If you call getOutput() this border is removed automatically by creating a sub-image.
- Connectivity is handled by child sub-classes. An index of neighbors could have been used, but the additional additional array access/loop slows things down a little bit.
- Watersheds are included. To remove them using RemoveWatersheds
- Pixel values are assumed to range from 0 to 255, inclusive.
[1] Vincent, Luc, and Pierre Soille. "Watersheds in digital spaces: an efficient algorithm based on immersion simulations." IEEE transactions on pattern analysis and machine intelligence 13.6 (1991): 583-598.

Nested Class Summary

Nested Classes
Modifier and Type	Class and Description
`static class`	`WatershedVincentSoille1991.Connect4` Implementation which uses a 4-connect rule
`static class`	`WatershedVincentSoille1991.Connect8` Implementation which uses a 8-connect rule

Field Summary

Fields
Modifier and Type	Field and Description
`protected int`	`currentDistance`
`protected int`	`currentLabel`
`protected boofcv.struct.image.GrayS32`	`distance`
`protected org.ddogleg.struct.CircularQueue_I32`	`fifo`
`protected org.ddogleg.struct.GrowQueue_I32[]`	`histogram`
`static int`	`INIT`
`static int`	`MARKER_PIXEL`
`static int`	`MASK`
`protected boofcv.struct.image.GrayS32`	`output`
`protected boofcv.struct.image.GrayS32`	`outputSub`
`protected RemoveWatersheds`	`removeWatersheds`
`static int`	`WSHED`

Constructor Summary

Constructors
Constructor and Description

WatershedVincentSoille1991()

Constructors
Constructor and Description
`WatershedVincentSoille1991()`

Method Summary

All Methods Instance Methods Abstract Methods Concrete Methods
Modifier and Type	Method and Description
`protected abstract void`	`assignNewToNeighbors(int index)` See if a neighbor has a label ( > 0 ) or has been assigned WSHED ( == 0 ).
`protected void`	`checkMask(int index)`
`protected abstract void`	`checkNeighborsAssign(int index)` Check the neighbors to see if it should become a member or a watershed
`protected abstract void`	`checkNeighborsMasks(int index)` Checks neighbors of pixel 'index' to see if their region is MASK, if so they are assigned the currentLabel and added to fifo.
`boofcv.struct.image.GrayS32`	`getOutput()` Segmented output image with watersheds.
`boofcv.struct.image.GrayS32`	`getOutputBorder()` The entire segmented image used internally.
`int`	`getTotalRegions()` Returns the total number of regions labeled.
`protected void`	`handleNeighborAssign(int indexTarget, int indexNeighbor)`
`void`	`process(boofcv.struct.image.GrayU8 input)` Perform watershed segmentation on the provided input image.
`void`	`process(boofcv.struct.image.GrayU8 input, boofcv.struct.image.GrayS32 seeds)` Segments the image using initial seeds for each region.
`void`	`removeWatersheds()` Removes watershed pixels from the output image by merging them into an arbitrary neighbor.
`protected void`	`sortPixels(boofcv.struct.image.GrayU8 input)` Very fast histogram based sorting.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Field Detail
  - WSHED
```
public static final int WSHED
```
    See Also:
    
    Constant Field Values
  - INIT
```
public static final int INIT
```
    See Also:
    
    Constant Field Values
  - MASK
```
public static final int MASK
```
    See Also:
    
    Constant Field Values
  - MARKER_PIXEL
```
public static final int MARKER_PIXEL
```
    See Also:
    
    Constant Field Values
  - histogram
```
protected org.ddogleg.struct.GrowQueue_I32[] histogram
```
  - output
```
protected boofcv.struct.image.GrayS32 output
```
  - outputSub
```
protected boofcv.struct.image.GrayS32 outputSub
```
  - distance
```
protected boofcv.struct.image.GrayS32 distance
```
  - currentDistance
```
protected int currentDistance
```
  - currentLabel
```
protected int currentLabel
```
  - fifo
```
protected org.ddogleg.struct.CircularQueue_I32 fifo
```
  - removeWatersheds
```
protected RemoveWatersheds removeWatersheds
```
- Constructor Detail
  - WatershedVincentSoille1991
```
public WatershedVincentSoille1991()
```
- Method Detail
  - process
```
public void process(boofcv.struct.image.GrayU8 input)
```
    Perform watershed segmentation on the provided input image. New basins are created at each local minima.
    
    Parameters:
    
    input - Input gray-scale image.
  - process
```
public void process(boofcv.struct.image.GrayU8 input,
                    boofcv.struct.image.GrayS32 seeds)
```
    Segments the image using initial seeds for each region. This is often done to avoid over segmentation but requires additional preprocessing and/or knowledge on the image structure. Initial seeds are specified in the input image 'seeds'. A seed is any pixel with a value > 0. New new regions will be created beyond those seeds. The final segmented image is provided by getOutput().
    
    NOTE: If seeds are used then getTotalRegions() will not return a correct solution.
    
    Parameters:
    
    input - (Input) Input image
    
    seeds - (Output) Segmented image containing seeds. Note that all seeds should have a value > 0 and have a value ≤ numRegions.
  - assignNewToNeighbors
```
protected abstract void assignNewToNeighbors(int index)
```
    See if a neighbor has a label ( > 0 ) or has been assigned WSHED ( == 0 ). If so set distance of pixel index to 1 and add it to fifo.
    
    Parameters:
    
    index - Pixel whose neighbors are being examined
  - checkNeighborsAssign
```
protected abstract void checkNeighborsAssign(int index)
```
    Check the neighbors to see if it should become a member or a watershed
    
    Parameters:
    
    index - Index of the target pixel
  - handleNeighborAssign
```
protected void handleNeighborAssign(int indexTarget,
                                    int indexNeighbor)
```
  - checkNeighborsMasks
```
protected abstract void checkNeighborsMasks(int index)
```
    Checks neighbors of pixel 'index' to see if their region is MASK, if so they are assigned the currentLabel and added to fifo.
    
    Parameters:
    
    index - Pixel whose neighbors are being examined.
  - checkMask
```
protected void checkMask(int index)
```
  - sortPixels
```
protected void sortPixels(boofcv.struct.image.GrayU8 input)
```
    Very fast histogram based sorting. Index of each pixel is placed inside a list for its intensity level.
  - getOutput
```
public boofcv.struct.image.GrayS32 getOutput()
```
    Segmented output image with watersheds. This is a sub-image of getOutputBorder() to remove the outside border of -1 valued pixels.
  - getOutputBorder
```
public boofcv.struct.image.GrayS32 getOutputBorder()
```
    The entire segmented image used internally. This contains a 1-pixel border around the entire image filled with pixels of value -1.
  - removeWatersheds
```
public void removeWatersheds()
```
    Removes watershed pixels from the output image by merging them into an arbitrary neighbor.
  - getTotalRegions
```
public int getTotalRegions()
```
    Returns the total number of regions labeled. If watersheds have not been removed then this will including the watershed.
    THIS IS NOT VALID IF SEEDS ARE USED!!!
    
    Returns:
    
    number of regions.

Class WatershedVincentSoille1991

Nested Class Summary

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

WSHED

INIT

MASK

MARKER_PIXEL

histogram

output

outputSub

distance

currentDistance

currentLabel

fifo

removeWatersheds

Constructor Detail

WatershedVincentSoille1991

Method Detail

process

process

assignNewToNeighbors

checkNeighborsAssign

handleNeighborAssign

checkNeighborsMasks

checkMask

sortPixels

getOutput

getOutputBorder

removeWatersheds

getTotalRegions