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# viscircles

## Syntax

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

## Description

example

````viscircles(centers,radii)` draws circles with specified `centers` and `radii` onto the current axes.```
````viscircles(ax,centers,radii)` draws circles onto the axes specified by `ax`.```
````h = viscircles(ax,centers,radii)` draws circles and returns a handle to the circles created. This handle is an `hggroup` object that is a child of the `axes` object, `ax`.```

example

````h = viscircles(___,Name,Value)` specifies additional options with one or more `Name,Value` pair arguments, using any of the previous syntaxes. Parameter names can be abbreviated.```

## Examples

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This example shows how to draw lines around both bight and dark circles in an image.

Read the image into the workspace and display it.

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

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');`

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

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

The `viscircles` function does not clear the target axes before plotting circles. To remove circles that have been previously plotted in an axes, use the `cla` function. 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'}; for k = 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]) % Set the axis aspect ratio to 1:1. axis square % Set a title. title(['k = ' num2str(k)]) % Display the circles. viscircles(centers,radii,'Color',colors{k}); % Pause for 1 second. pause(1) end ```

## Input Arguments

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Coordinates of circle centers, specified as a `P`-by-`2` matrix, such as that obtained from `imfindcircles`. The x-coordinates of the circle centers are in the first column and the y-coordinates are in the second column. The coordinates can be integers (of any numeric type) or floating-point values (of type `double` or `single`).

Data Types: `single` | `double` | `int8` | `int16` | `int32` | `int64` | `uint8` | `uint16` | `uint32` | `uint64`

Circle radii, specified as a column vector such as that returned by `imfindcircles`. The radius value at `radii(j)` corresponds to the circle with center coordinates `centers(j,:)`. The values of `radii` can be nonnegative integers (of any numeric type) or floating-point values (of type `double` or `single`).

Data Types: `single` | `double` | `int8` | `int16` | `int32` | `int64` | `uint8` | `uint16` | `uint32` | `uint64`

Axes in which to draw circles, specified as a handle object returned by `gca` or `axes`.

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 single quotes (`' '`). You can specify several name and value pair arguments in any order as `Name1,Value1,...,NameN,ValueN`.

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

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Augment drawn circles with contrasting features to improve visibility, specified as a logical value `true` or `false`. If you set the value to `true`, `viscircles` draws a contrasting circle below the colored circle.

Data Types: `logical`

Color of circle edges, specified as a MATLAB® `ColorSpec` value.

Line style of circle edge, specified as the comma-separated pair consisting of `'LineStyle'` and any line specifier in the table below.

Line StyleDescriptionResulting Line
`'-'`Solid line

`'--'`Dashed line

`':'`Dotted line

`'-.'`Dash-dotted line

`'none'`No lineNo line

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

## Output Arguments

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Circles drawn, returned as a handle to an `hggroup` object. This object is a child of the `axes` object, `ax`.

## See Also

#### Introduced in R2012a

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