label2rgb() - Image Processing

RGB = label2rgb(L) converts
a label matrix, L, such as those returned by labelmatrix, bwlabel, bwlabeln,
or watershed, into an RGB color image for the purpose
of visualizing the labeled regions. The label2rgb function
determines the color to assign to each object based on the number
of objects in the label matrix and range of colors in the colormap.
The label2rgb function picks colors from the entire
range.RGB = label2rgb(L, map) defines
the colormap map to be used in the RGB image. map can
have any of the following values:n-by-3 colormap matrixString containing the name of a MATLAB® colormap
function, such as 'jet' or 'gray' (See colormap for a list of supported colormaps.)Function handle of a colormap function, such as @jet or @gray If you do not specify map, the default value
is 'jet'.RGB = label2rgb(L, map, zerocolor) defines
the RGB color of the elements labeled 0 (zero)
in the input label matrix L. As the value of zerocolor,
specify an RGB triple or one of the strings listed in this table. ValueColor
'b'Blue
'c'Cyan
'g' Green
'k'Black
'm'Magenta
'r'Red
'w'White
'y'Yellow
If you do not specify zerocolor, the default
value for zero-labeled elements is [1 1 1] (white).RGB = label2rgb(L, map, zerocolor,
order) controls how label2rgb assigns
colormap colors to regions in the label matrix. If order is 'noshuffle' (the
default), label2rgb assigns colormap colors to
label matrix regions in numerical order. If order is 'shuffle', label2rgb assigns
colormap colors pseudorandomly.Code Generation support:
Yes.MATLAB Function Block support:
Yes.

Syntax

RGB = label2rgb(L)RGB = label2rgb(L, map)RGB = label2rgb(L, map, zerocolor)RGB = label2rgb(L, map, zerocolor,
order)

Example

Use Color to Highlight Elements in a Label MatrixOpen This Example
Read an image and display it.I = imread('rice.png');
figure, imshow(I)

Create a label matrix from the image.BW = im2bw(I, graythresh(I));
CC = bwconncomp(BW);
L = labelmatrix(CC);
Convert the label matrix into RGB image, using default settings.RGB = label2rgb(L);
figure, imshow(RGB)

Convert label matrix into RGB image, specifying optional parameters.RGB2 = label2rgb(L, 'spring', 'c', 'shuffle');
figure, imshow(RGB2)

Output / Return Value

Limitations

Alternatives / See Also

Reference