Image segmentation

../../../../_images/image_segmentation.svg

Segments an input color or grayscale image into regions with integer labels

Documentation

Algorithms

Chan-Vese

Active contour model based segmentation starting from an evolving level set. Can be used to segment objects without clearly defined boundaries.

iter:

Maximum number of iterations of algoritm

mu:

Edge length parameter. Higher values will produce rounder edges while smaller values will detect smaller objects

lambda1:

Difference-from-average weight parameter. Affects the total area labelled positive

lambda2:

Difference-from-average weight parameter. Affects the total area labelled negative

dt:

Multiplicative factor speeding up calculation at risk for non-convergence

initial level set:

Starting level set

morphological:

If true then use morphological Chan-Vese instead

Felzenszwalb

Oversegmentation of a multichannel image based on minimum spanning trees on the image grid.

sigma:

Standard deviation of gaussian kernel used in pre-processing (0.8)

scale:

Observation level, higher number means larger clusters

min size:

Minimum size of each component

K-means

Segments image using K-means clustering in color and spatial space.

n:

Number of clusters for K-means

compactness:

Balances color proximity and space proximity. Higher values give more weight to space proximity, making superpixel shapes more square/cubic. In SLICO mode, this is the initial compactness. This parameter depends strongly on image contrast and on the shapes of objects in the image. We recommend exploring possible values on a log scale, e.g., 0.01, 0.1, 1, 10, 100, before refining around a chosen value.

iter:

Maximum number of iterations of K-means

sigma:

Width of a gaussian kernel used to smooth image before K-means

CIE Lab:

If true (default) then image is converted to CIE-LAB colorspace before K-means, afterwards converted back to RGB. Image must be a 3 channel RGB image

force connectivity:

Forces the generated segments to be continous

Quickshift

Segments image using quickshift clustering in color and spatial space. Requires RGB images as inputs.

sigma:

Width of a gaussian kernel used to smooth image before K-means

ratio:

A value between 0.0 to 1.0. Balances between color and image space proximity

kernel size:

Width of gaussian kernel smoothing sample density. Higher values mean fewer clusters.

max dist:

Cut-off point for data distances. Higher means fewer clusters.

CIE Lab:

If true (default) then image is converted to CIE-LAB colorspace before K-means. Image must be a 3 channel RGB image

Watershed

Floods watershed basins based on a set of N markers, suitable for grayscale images

n:

Desired number of markers

compact:

If not zero then use the compact-watershed algorithm giving more regularly shaped basins

line:

Draws a one-pixel area with value=0 around each region

Definition

Input ports

source image

source image to segment

Output ports

result image

result after segmentation

Configuration

CIE Lab (CIE Lab)

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Algorithm (algorithm)

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compact (compact)

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compactness (compactness)

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dt (dt)

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force connectivity (force connectivity)

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initial level set (initial level set)

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iter (iter)

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kernel size (kernel size)

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lambda1 (lambda1)

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lambda2 (lambda2)

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line (line)

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max dist (max dist)

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min size (min size)

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morphological (morphological)

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mu (mu)

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n (n)

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ratio (ratio)

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scale (scale)

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sigma (sigma)

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Examples

Implementation

class node_segmentation.Segmentation[source]