labeloverlay

Overlay label matrix regions on 2-D image

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Syntax

B = labeloverlay(A,L)
B = labeloverlay(A,BW)
B = labeloverlay(A,C)
B = labeloverlay(___,Name,Value)

Description

example

B = labeloverlay(A,L) fuses the input image, A, with a different color for each nonzero label in label matrix L. The labeloverlay function does not fuse background pixels with a color.

example

B = labeloverlay(A,BW) fuses the input image with a color where mask BW is true. The labeloverlay function does not fuse background pixels (labeled false ) with a color.

B = labeloverlay(A,C) fuses the input image with a different color for each label in categorical matrix C. The labeloverlay function does not fuse pixels of the <undefined> category with a color.

example

B = labeloverlay(___,Name,Value) computes the fused overlay image, B, using Name,Value pairs to control aspects of the computation.

Examples

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Open Live Script

Read an image, then segment it using superpixels.

A = imread('kobi.png');
[L,N] = superpixels(A,20);

Fuse the segmentation results with the original image. Display the fused image.

B = labeloverlay(A,L);
imshow(B)

Open Live Script

Read a grayscale image and display it.

A = imread('coins.png');
imshow(A)

Create a mask using binary thresholding.

t = graythresh(A);
BW = imbinarize(A,t);
imshow(BW)

Fuse the mask with the original image. Display the fused image.

B = labeloverlay(A,BW);
imshow(B)

Open Live Script

Read a grayscale image and create a mask using binary thresholding.

A = imread('coins.png');
t = graythresh(A);
BW = imbinarize(A,t);

Create categorical labels based on the image contents.

stringArray = repmat("table",size(BW));
stringArray(BW) = "coin";
categoricalSegmentation = categorical(stringArray);

Fuse the categorical segmentation with the original image. Display the fused image.

B = labeloverlay(A,categoricalSegmentation);
imshow(B)

Fuse the original image with only one label from the categorical segmentation. Change the colormap and make the labels more opaque, and display the result.

C = labeloverlay(A,categoricalSegmentation,'IncludedLabels',"coin",...
    'Colormap','autumn','Transparency',0.25);
imshow(C)

Input Arguments

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Input image, specified as a 2-D grayscale or color image.

Data Types: single | double | int8 | int16 | uint8 | uint16

Labels, specified as a matrix of nonnegative integers.

Data Types: single | double | int8 | int16 | int32 | uint8 | uint16 | uint32

Mask, specified as a logical matrix.

Data Types: logical

Category labels, specified as a categorical matrix.

Data Types: categorical

Name-Value Pair Arguments

Specify optional comma-separated pairs of Name,Value arguments. Name is the argument name and Value is the corresponding value. Name must appear inside quotes. You can specify several name and value pair arguments in any order as Name1,Value1,...,NameN,ValueN.

Example: labeloverlay(myImage,myLabels,'Colormap','hot') displays labels in colors from the 'hot' color map.

Color map, specified as the comma-separated pair consisting of 'Colormap' and one of these values:

  • An l-by-3 color map. RGB triplets in each row of the color map must be normalized to the range [0, 1]. l is the number of labels in label matrix L, binary mask BW, or categorical matrix C.

  • A string or character vector corresponding to one of the valid inputs to the colormap function. labeloverlay permutes the specified color map so that adjacent labels are more distinct.

Example: [0.2, 0.1, 0.5; 0.1, 0.5, 0.8]

Example: 'hot'

Data Types: single | double | char | string

Labels to display in the fused image, specified as the comma-separated pair consisting of 'IncludedLabels' and one of the following:

  • An integer, or vector of integers, in the range [0, max(L(:))]. By default, labeloverlay displays all nonzero labels.

  • A string, or vector of strings, corresponding to labels in categorical matrix C. By default, labeloverlay displays all defined categorical labels.

Any label not included in the vector is considered the background. For example, in the vector [1,3,4], the value 2 would be considered the background, if it existed as a label.

Example: [1,3,4]

Example: ["flower","stem"]

Data Types: single | double | int8 | int16 | int32 | uint8 | uint16 | uint32 | string

Transparency of displayed labels, specified as the comma-separated pair consisting of 'Transparency' and a number in the range [0, 1].

  • A value of 0 makes the colored labels completely opaque.

  • A value of 1 makes the colored labels completely transparent.

Data Types: single | double

Output Arguments

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Fused image, returned as a numeric matrix of the same size as A.

Data Types: uint8

See Also

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Topics

Introduced in R2017b

Image Processing Toolbox Documentation

Support