visboundaries
Plot region boundaries
Syntax
Description
visboundaries( draws boundaries of regions in the
binary image BW)BW on the current axes. BW is
a 2-D binary image where pixels that are logical true belong to
the foreground region and pixels that are logical false
constitute the background. visboundaries uses bwboundaries to find the boundary
pixel locations in the image.
visboundaries( draws region boundaries
specified by B)B, where B is a cell array
containing the boundary pixel locations of the regions, similar in structure to the
first output from bwboundaries.
visboundaries( draws
region boundaries on the axes specified by ax,___)ax.
visboundaries(___, uses
name-value pair arguments to specify additional properties of the boundaries.Name,Value)
h = visboundaries(___)h, for the boundaries.
Examples
Compute Boundaries and Plot on Image
Read image.
BW = imread('blobs.png');Compute boundaries.
B = bwboundaries(BW);
Display image and plot boundaries on image.
imshow(BW)
hold on
visboundaries(B)
Visualize Segmentation Result
Read image and display it.
I = imread('toyobjects.png'); imshow(I) hold on
Segment the image using the active contours (snakes) algorithm. First, specify the initial contour location close to the object that is to be segmented.
mask = false(size(I)); mask(50:150,40:170) = true;
Display the initial contour on the original image in blue.
visboundaries(mask,'Color','b');
Segment the image using the 'edge' method using 200 iterations.
bw = activecontour(I, mask, 200, 'edge');Display the final contour on the original image in red.
visboundaries(bw,'Color','r'); title('Blue - Initial Contour, Red - Final Contour');
Input Arguments
BW — Binary image
logical array
Binary image, specified as a logical array.
Data Types: logical
B — Boundary pixel locations
cell array of Q-by-2 matrices
Boundary pixel locations, specified as a cell array. Each cell contains a Q-by-2 matrix, where Q is the number of boundary pixels for the corresponding region. Each row of these Q-by-2 matrices contains the row and column coordinates of a boundary pixel.
Data Types: cell
ax — Image on which to draw boundaries
current axes (default) | axes object
Image on which to draw boundaries, specified as an axes object.
Data Types: double
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.
visboundaries(bw,'Color','b');'Color' — Color of boundary
'red' (default) | RGB triplet | hexadecimal color code | color name | short color name
Color of the boundary, specified as an RGB triplet, a hexadecimal color code, a color name, or a short color name.
For a custom color, specify an RGB triplet or a hexadecimal color code.
An RGB triplet is a three-element row vector whose elements specify the intensities of the red, green, and blue components of the color. The intensities must be in the range
[0,1]; for example,[0.4 0.6 0.7].A hexadecimal color code is a character vector or a string scalar that starts with a hash symbol (
#) followed by three or six hexadecimal digits, which can range from0toF. The values are not case sensitive. Thus, the color codes'#FF8800','#ff8800','#F80', and'#f80'are equivalent.
Alternatively, you can specify some common colors by name. This table lists the named color options, the equivalent RGB triplets, and hexadecimal color codes.
| Color Name | Short Name | RGB Triplet | Hexadecimal Color Code | Appearance |
|---|---|---|---|---|
'red' | 'r' | [1 0 0] | '#FF0000' |
|
'green' | 'g' | [0 1 0] | '#00FF00' |
|
'blue' | 'b' | [0 0 1] | '#0000FF' |
|
'cyan'
| 'c' | [0 1 1] | '#00FFFF' |
|
'magenta' | 'm' | [1 0 1] | '#FF00FF' |
|
'yellow' | 'y' | [1 1 0] | '#FFFF00' |
|
'black' | 'k' | [0 0 0] | '#000000' |
|
'white' | 'w' | [1 1 1] | '#FFFFFF' |
|
'none' | Not applicable | Not applicable | Not applicable | No color |
Here are the RGB triplets and hexadecimal color codes for the default colors MATLAB® uses in many types of plots.
| RGB Triplet | Hexadecimal Color Code | Appearance |
|---|---|---|
[0 0.4470 0.7410] | '#0072BD' |
|
[0.8500 0.3250 0.0980] | '#D95319' |
|
[0.9290 0.6940 0.1250] | '#EDB120' |
|
[0.4940 0.1840 0.5560] | '#7E2F8E' |
|
[0.4660 0.6740 0.1880] | '#77AC30' |
|
[0.3010 0.7450 0.9330] | '#4DBEEE' |
|
[0.6350 0.0780 0.1840] | '#A2142F' |
|
Example: visboundaries(bw,'Color','r');
Example: visboundaries(bw,'Color','green');
Example: visboundaries(bw,'Color',[0 0
1]);
Example: visboundaries(bw,'Color','#FF8800');
'LineStyle' — Style of boundary line
'-' (default) | '--' | ':' | '-.' | 'none'
Line style of boundary edge, specified as the comma-separated pair
consisting of 'LineStyle' and any line specifier in
the table below.
| Line Style | Description | Resulting Line |
|---|---|---|
'-' | Solid line |
|
'--' | Dashed line |
|
':' | Dotted line |
|
'-.' | Dash-dotted line |
|
'none' | No line | No line |
Example: visboundaries(bw,'LineStyle','-.');
'LineWidth' — Width of the line used for the boundary
2 (default) | positive number
Width of the line used for the boundary, specified as a positive number. Specify this value in points, where one point = 1/72 inch.
Example: visboundaries(bw,'LineWidth',4);
Data Types: single | double | int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64
'EnhanceVisibility' — Augment the drawn boundary with contrasting features
true (default) | false
Augment the drawn boundary with contrasting features to improve
visibility on a varying background, specified as the logical flag true or false.
Example: visboundaries(bw,'EnhanceVisibility',true);
Data Types: logical