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viscircles

Create circle

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Syntax

viscircles(centers,radii)
viscircles(ax,centers,radii)
viscircles(___,Name,Value)
h = viscircles(___)

Description

example

viscircles(centers,radii)draws circles with specifiedcentersandradiionto the current axes. You can use theimfindcirclesfunction to find the centers and radii of circles in an image.

viscircles(ax,centers,radii)draws circles onto the axes specified byax.

viscircles(___,Name,Value)uses name-value arguments to specify additional properties of the circles.

h= viscircles(___)returns a handle,h, to the drawn circles.

Examples

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Open Live Script

Read the image into the workspace and display it.

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

Figure contains an axes object. The axes object contains an object of type image.

Define the radius range.

Rmin = 30; Rmax = 65;

Find all the bright circles in the image within the radius range.

[centersBright, radiiBright] = imfindcircles(A,[Rmin Rmax],'ObjectPolarity','bright');

Find all the dark circles in the image within the radius range.

[centersDark, radiiDark] = imfindcircles(A,[Rmin Rmax],'ObjectPolarity','dark');

Draw blue lines around the edges of the bright circles.

viscircles(centersBright, radiiBright,'Color','b');

Figure contains an axes object. The axes object contains 3 objects of type line, image.

Draw red dashed lines around the edges of the dark circles.

viscircles(centersDark, radiiDark,'LineStyle','--');

Figure contains an axes object. The axes object contains 5 objects of type line, image.

Open Live Script

Theviscirclesfunction does not clear the target axes before plotting circles. To remove circles that have been previously plotted in an axes, use theclafunction. To illustrate, this example creates a new figure and then loops, drawing a set of circles with each iteration, clearing the axes each time.

figure colors = {'b','r','g','y','k'};fork = 1:5% Create 5 random circles to display,X = rand(5,1); Y = rand(5,1); centers = [X Y]; radii = 0.1*rand(5,1);% Clear the axes.cla% Fix the axis limits.xlim([-0.1 1.1]) ylim([-0.1 1.1])%设置轴长宽比为1:1。axissquare% Set a title.title(['k = 'num2str(k)])% Display the circles.viscircles(centers,radii,'Color',colors{k});% Pause for 1 second.pause(1)end

Figure contains an axes object. The axes object with title k = 5 contains 2 objects of type line.

Input Arguments

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Coordinates of circle centers, specified as a two-column numeric matrix. Thex-coordinates of the circle centers are in the first column and they-coordinates are in the second column.

Circle radii, specified as a positive number or a column vector of positive numbers of the same length ascenters. Whenradiiis a positive number,viscirclesdraws all circles with the same radius. Whenradiiis a column vector,viscirclesdraws each circlecenters(j,:)with the corresponding radiusradii(j).

Axes in which to draw circles, specified as anAxesobject returned bygcaoraxes.

Name-Value Arguments

Specify optional pairs of arguments asName1=Value1,...,NameN=ValueN, whereNameis the argument name andValueis the corresponding value. Name-value arguments must appear after other arguments, but the order of the pairs does not matter.

Example:viscircles(centers,radii,Color="b")specifies blue circle edges, using the short color name for blue.

Before R2021a, use commas to separate each name and value, and encloseNamein quotes.

Example:viscircles(centers,radii,"Color","b")specifies blue circle edges, using the short color name for blue.

Augment drawn circles with contrasting features to improve visibility, specified as a logical valuetrueorfalse. If you set the value totrue, thenviscirclesdraws a contrasting circle below the colored circle.

Data Types:logical

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 string scalar or character vector that starts with a hash symbol (#) followed by three or six hexadecimal digits, which can range from0toF. The values are not case sensitive. Therefore, 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"

Sample of the color red
"green" "g" [0 1 0] "#00FF00"

Sample of the color green
"blue" "b" [0 0 1] "#0000FF"

Sample of the color blue
"cyan" "c" [0 1 1] "#00FFFF"

Sample of the color cyan
"magenta" "m" [1 0 1] "#FF00FF"

Sample of the color magenta
"yellow" "y" [1 1 0] “# FFFF00”

Sample of the color yellow
"black" "k" [0 0 0] "#000000"

Sample of the color black
"white" "w" [1 1 1] "#FFFFFF"

Sample of the color white
"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"

Sample of RGB triplet [0 0.4470 0.7410], which appears as dark blue
[0.8500 0.3250 0.0980] "#D95319"

Sample of RGB triplet [0.8500 0.3250 0.0980], which appears as dark orange
[0.9290 0.6940 0.1250] "#EDB120"

Sample of RGB triplet [0.9290 0.6940 0.1250], which appears as dark yellow
[0.4940 0.1840 0.5560] "#7E2F8E"

Sample of RGB triplet [0.4940 0.1840 0.5560], which appears as dark purple
[0.4660 0.6740 0.1880] "#77AC30"

Sample of RGB triplet [0.4660 0.6740 0.1880], which appears as medium green
[0.3010 0.7450 0.9330] "#4DBEEE"

Sample of RGB triplet [0.3010 0.7450 0.9330], which appears as light blue
[0.6350 0.0780 0.1840] "#A2142F"

Sample of RGB triplet [0.6350 0.0780 0.1840], which appears as dark red

Example:viscircles(centers,radii,'Color','r');

Example:viscircles(centers,radii,'Color','green');

Example:viscircles(centers,radii,'Color',[0 0 1]);

Example:viscircles(centers,radii,'Color','#FF8800');

Line style of circle 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

Sample of solid line
"--" Dashed line

Sample of dashed line
":" Dotted line

Sample of dotted line
"-." Dash-dotted line

Sample of dash-dotted line, with alternating dashes and dots
"none" No line No line

Width of circle edge, specified a positive number. Line width is expressed in points, where each point equals 1/72 of an inch.

Data Types:double

Output Arguments

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Circles drawn, returned as anhggroupobject.his the child of the axesaxif specified, otherwisehis the child of the current axes.

Version History

Introduced in R2012a

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See Also

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