Draw Shapes

Draw rectangles, lines, polygons, or circles on images

Library:
Computer Vision Toolbox / Text & Graphics

Description

The Draw Shapes block draws rectangles, lines, polygons, or circles on images by overwriting pixel values. As a result, the shapes are embedded in the output image. The block uses Bresenham's line drawing algorithm to draw lines, polygons, and rectangles and Bresenham's circle drawing algorithm to draw circles. The output signal is the same size and data type as the inputs to the Image, R, G, and B ports.

You can set the shape fill or border color via the input port or by manually entering the values in the Block Parameters window. Use the color parameters to determine the appearance of the rectangles, lines, polygons, or circles.

Ports

Input

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`Image` — Input image
M-by-N matrix of intensity values | M-by-N-by-P color values

Input image, specified as either an M-by-N matrix of intensity values or an M-by-N-by-P matrix of color values with P color planes.

`R` — Red video stream
scalar | vector | matrix

Red video stream, specified as a scalar, vector, or a matrix. The input represents one plane of the RGB video stream. The R, G, and B ports must have the same dimensions and data type.

Dependencies

To enable this port, set the Image signal parameter to Separate color signals.

`G` — Green video stream
scalar | vector | matrix

Green video stream, specified as a scalar, vector, or a matrix. The input represents one plane of the RGB video stream. The R, G, and B ports must have the same dimensions and data type.

Dependencies

To enable this port, set the Image signal parameter to Separate color signals.

`B` — Blue video stream
scalar | vector | matrix

Blue video stream, specified as a scalar, vector, or a matrix. The input represents one plane of the RGB video stream. The R, G, and B ports must have the same dimensions and data type.

Dependencies

To enable this port, set the Image signal parameter to Separate color signals.

`Pts` — Shape coordinates
M-by-3 matrix | M-by-4 matrix | M-by-2L

Shape coordinates. The format of the points depends on the type of shape you specify with the Shape parameter.

Rectangles — M-by-4 matrix of M rectangles. The format for each rectangle must be, [x y width height].

Shape Input to the Pts Port Drawn Shape

Single Rectangle

Shape	Input to the Pts Port	Drawn Shape
Single Rectangle	Four-element row vector in the format `[x y width height]`, where: `x` and `y` are the one-based coordinates of the upper-left corner of the rectangle. `width` and `height` are the width and height in pixels, of the rectangle. The values of `width` and `height` must be greater than 0.
M Rectangles	M-by-4 matrix in the format $[\begin{matrix} x_{1} & y_{1} & w i d t h_{1} & h e i g h t_{1} \\ x_{2} & y_{2} & w i d t h_{2} & h e i g h t_{2} \\ ⋮ & ⋮ & ⋮ & ⋮ \\ x_{M} & y_{M} & w i d t h_{M} & h e i g h t_{M} \end{matrix}]$ ,where each row of the matrix corresponds to a different rectangle and is of the same form as the vector for a single rectangle.

Four-element row vector in the format
[x y width height], where:

x and y are the one-based coordinates of the upper-left corner of the rectangle.
width and height are the width and height in pixels, of the rectangle. The values of width and height must be greater than 0.

M Rectangles

M-by-4 matrix in the format

$[\begin{matrix} x_{1} & y_{1} & w i d t h_{1} & h e i g h t_{1} \\ x_{2} & y_{2} & w i d t h_{2} & h e i g h t_{2} \\ ⋮ & ⋮ & ⋮ & ⋮ \\ x_{M} & y_{M} & w i d t h_{M} & h e i g h t_{M} \end{matrix}]$

,where each row of the matrix corresponds to a different rectangle and is of the same form as the vector for a single rectangle.

Lines — M-by-2L matrix of M polylines. The format for each polyline must be of the form [x1,y1,x2,y2,…,xL,yL].

Shape	Input to the Pts Port	Drawn Shape
Single Line	Four-element row vector in the format `[x₁ y₁ x₂ y₂]`, where: `x₁` and `y₁` are the coordinates of the beginning of the line. `x₂` and `y₂` are the coordinates of the end of the line.
M Lines	M-by-4 matrix in the format $[\begin{matrix} x_{11} & y_{11} & x_{12} & y_{12} \\ x_{21} & y_{21} & x_{22} & y_{22} \\ ⋮ & ⋮ & ⋮ & ⋮ \\ x_{M 1} & y_{M 1} & x_{M 2} & y_{M 2} \end{matrix}]$ ,where each row of the matrix corresponds to a different line and is of the same form as the vector for a single line.
Single Polyline with (L-1) Segments	Vector of size 2L, where L is the number of vertices, in the format, `[x₁, y₁, x₂, y₂, ..., x_L, y_L`, where x₁ and y₁ are the coordinates of the beginning of the first line segment. x₂ and y₂ are the coordinates of the end of the first line segment and the beginning of the second line segment. x_L and y_L are the coordinates of the end of the (L-1)^th line segment. The polyline always contains (L-1) number of segments because the first and last vertex points do not connect. The block produces an error message when the number of rows is less than two or not a multiple of two.
M Polylines with (L-1) Segments	M-by-2L matrix in the format $[\begin{matrix} x_{11} & y_{11} & x_{12} & y_{12} & \dots & x_{1 L} & y_{1 L} \\ x_{21} & y_{21} & x_{22} & y_{22} & \dots & x_{2 L} & y_{2 L} \\ ⋮ & ⋮ & ⋮ & ⋮ & ⋱ & ⋮ & ⋮ \\ x_{M 1} & y_{M 1} & x_{M 2} & y_{M 2} & \dots & x_{M L} & y_{M L} \end{matrix}]$ , where each row of the matrix corresponds to a different polyline and is of the same form as the vector for a single polyline. When you require one polyline to contain less than (L–1) number of segments, fill the matrix by repeating the coordinates of the last vertex. The block produces an error message if the number of rows is less than two or not a multiple of two.

Polygons — M-by-2L matrix of M polygons. The format for each polygon must be of the form [x1,y1,x2,y2,…,xL,yL]. The points are specified in consecutive order to form a polygon.

Shape Input to the Pts Port Drawn Shape

Shape	Input to the Pts Port	Drawn Shape
Single Polygon with L line segments	Row vector of size 2L, where L is the number of vertices, in the format `[x₁ y₁ x₂ y₂ ... x_L y_L]`, where: x₁ and y₁ are the coordinates of the beginning of the first line segment. x₂ and y₂ are the coordinates of the end of the first line segment and the beginning of the second line segment. x_L and y_L are the coordinates of the end of the (L-1)^th line segment and the beginning of the L^th line segment. The block connects `[x₁ y₁]` to `[x_L y_L]` to complete the polygon. The block produces an error if the number of rows is negative or not a multiple of two.
M Polygons with the largest number of line segments in any line being L	M-by-2L matrix in the format $[\begin{matrix} x_{11} & y_{11} & x_{12} & y_{12} & \dots & x_{1 L} & y_{1 L} \\ x_{21} & y_{21} & x_{22} & y_{22} & \dots & x_{2 L} & y_{2 L} \\ ⋮ & ⋮ & ⋮ & ⋮ & ⋱ & ⋮ & ⋮ \\ x_{M 1} & y_{M 1} & x_{M 2} & y_{M 2} & \dots & x_{M L} & y_{M L} \end{matrix}]$ , where each row of the matrix corresponds to a different polygon and is of the same form as the vector for a single polygon. If some polygons are shorter than others, repeat the ending coordinates to fill the polygon matrix. The block produces an error message if the number of rows is less than two or is not a multiple of two.

Single Polygon with L line segments

Row vector of size 2L, where L is the number of vertices, in the format

[x₁ y₁
                                  x₂ y₂ ...
                                  x_L y_L]

, where:

x₁ and y₁ are the coordinates of the beginning of the first line segment.
x₂ and y₂ are the coordinates of the end of the first line segment and the beginning of the second line segment.
x_L and y_L are the coordinates of the end of the (L-1)^th line segment and the beginning of the L^th line segment.

The block connects

[x₁
                                  y₁]

[x_L
                                y_L]

to complete the polygon. The block produces an error if the number of rows is negative or not a multiple of two.

M Polygons with the largest number of line segments in any line being L

M-by-2L matrix in the format

$[\begin{matrix} x_{11} & y_{11} & x_{12} & y_{12} & \dots & x_{1 L} & y_{1 L} \\ x_{21} & y_{21} & x_{22} & y_{22} & \dots & x_{2 L} & y_{2 L} \\ ⋮ & ⋮ & ⋮ & ⋮ & ⋱ & ⋮ & ⋮ \\ x_{M 1} & y_{M 1} & x_{M 2} & y_{M 2} & \dots & x_{M L} & y_{M L} \end{matrix}]$

, where each row of the matrix corresponds to a different polygon and is of the same form as the vector for a single polygon. If some polygons are shorter than others, repeat the ending coordinates to fill the polygon matrix.

The block produces an error message if the number of rows is less than two or is not a multiple of two.

Circles — M-by-3 matrix of M circles. The format for each circle must be, [x y radius].

Shape Input to the Pts Port Drawn Shape

Single Circle

Shape	Input to the Pts Port	Drawn Shape
Single Circle	Three-element row vector in the format `[x y radius]`, where: `x` and `y` are coordinates for the center of the circle. `radius` is the radius of the circle, which must be greater than 0.
M Circles	M-by-3 matrix in the format $[\begin{matrix} x_{1} & y_{1} & r a d i u s_{1} \\ x_{2} & y_{2} & r a d i u s_{2} \\ ⋮ & ⋮ & ⋮ \\ x_{M} & y_{M} & r a d i u s_{M} \end{matrix}]$ , where each row of the matrix corresponds to a different circle and is of the same form as the vector for a single circle.

Three-element row vector in the format
[x y radius], where:

x and y are coordinates for the center of the circle.
radius is the radius of the circle, which must be greater than 0.

M Circles

M-by-3 matrix in the format

$[\begin{matrix} x_{1} & y_{1} & r a d i u s_{1} \\ x_{2} & y_{2} & r a d i u s_{2} \\ ⋮ & ⋮ & ⋮ \\ x_{M} & y_{M} & r a d i u s_{M} \end{matrix}]$

, where each row of the matrix corresponds to a different circle and is of the same form as the vector for a single circle.

Dependencies

Double-precision floating point is only supported if the input to the Image or R, G, and B ports is floating point.
Single-precision floating point (only supported if the input to the Image or R, G, and B ports is floating point).

`ROI` — Region of interest
four-element vector

Region of interest, specified as a four-element vector [x y width height]. The region defines a rectangular area to draw shapes. The first two elements represent the one-based coordinates of the upper-left corner of the area. The second two elements represent the width and height of the area.

Dependencies

To enable this port, set the ROI port appears when you set the Draw shapes in parameter to Specify region of interest via port.

`Clr` — Color of shape
P-element vector | M-by-P matrix

Color of shape, specified as either a P-element vector or an M-by-P matrix of M number of shapes and P number of color planes. You can specify a color (RGB) for each shape, or specify one color for all shapes.

Dependencies

To enable this port, set the Border color source parameter to Input port.

Output

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`Port_1` — Output image
scalar | vector | matrix

Output image, returned as a scalar, vector, or matrix.

Parameters

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Main Tab

`Fill Shapes` — Fill color
off (default) | on

Select Fill Shapes to specify an intensity value or a color.

Note

If you are generating code and you select the Fill shapes check box, the word length of the block input(s) cannot exceed 16 bits.

`Fill color source` — Source for fill color
`Specify via dialog` (default) | `Input port`

Specify the source for the fill color value to either Specify via dialog or Input port.

Dependencies

To enable this parameter, select Fill shapes.

`Fill color` — Shape fill color
`Black` (default) | `White` | `User-specified value`

Specify the shape fill color.

Dependencies

To enable this parameter, select the Fill shapes parameter.

`Border color source` — Border color source
(default) |

Specify the source for the border color value to either Specify via dialog or Input port.

Dependencies

To enable this parameter, select the Fill shapes parameter.

`Border color` — Border color
`Black` (default) | `White` | `User-specified value`

Specify the appearance of the shape's border. You can specify Black, White, or User-specified value. This table describes what to enter for the color value based on the block input and the number of shapes you are drawing.

Block Input	Color Value(s) for Drawing One Shape or Multiple Shapes with the Same Color	Color Value(s) for Drawing Multiple Shapes with Unique Colors
Intensity image	Scalar intensity value	R-element vector where R is the number of shapes
Color image	P-element vector where P is the number of color planes	R-by-P matrix where P is the number of color planes and R is the number of shapes

For each value in the Color Value(s) parameter, enter a number between the minimum and maximum values that can be represented by the data type of the input image. If you enter a value outside this range, the block produces an error message.

Dependencies

To enable this parameter, clear the Fill shapes parameter.

`Color value(s)` — Color value
color value | intensity value

Specify an intensity or color value for the shape's border or fill.

Tunable: Yes

Dependencies

To enable this parameter set the Border color or Fill color parameter to User-specified value.

`Opacity factor (between 0 and 1)` — Opacity factor
value in the range [0,1] | R-element vector

Specify the opacity of the shading inside the shape, where 0 is transparent and 1 is opaque.

Opacity Factor value for Drawing One Shape or Multiple Shapes with the Same Color	Opacity Factor value for Drawing Multiple Shapes with Unique Colors
Scalar intensity value	R-element vector where R is the number of shapes

Dependencies

To enable this parameter, clear the Fill shapes parameter.

`Use antialiasing` — Smoothing algorithm
off | on

Perform a smoothing algorithm on the line, polygon, or circle.

Dependencies

To enable this parameter, set the Shape parameter to either Lines, Polygons, or Circles.

`Image Signal` — Image signal

Specify how to input and output a color video signal. Select the color video signal as one of the following:

One multidimensional signal — The block accepts an M-by-N-by-P color video signal, where P is the number of color planes, at one port.
Separate color signals — Enables the R,G, and B input ports. Each port accepts one M-by-N plane of an RGB video stream.

Data Types Tab

For details on the fixed-point block parameters, see Specify Fixed-Point Attributes for Blocks.

Model Examples

Draw Rectangles on Image

Draw rectangles on an image by overwriting the pixel values of the input image.

Open Model

Draw Circles on Image

Draw circles on an image by overwriting the pixel values of the input image.

Open Model

Block Characteristics

Data Types	`Boolean` \| `double` \| `fixed point` \| `integer` \| `single`
Multidimensional Signals	`yes`
Variable-Size Signals	`yes`

Extended Capabilities

C/C++ Code Generation
Generate C and C++ code using Simulink® Coder™.

Fixed-Point Conversion
Design and simulate fixed-point systems using Fixed-Point Designer™.

Version History

Introduced before R2006a

Draw Shapes

Description

Ports

Input

Image — Input image M-by-N matrix of intensity values | M-by-N-by-P color values

R — Red video stream scalar | vector | matrix

Dependencies

G — Green video stream scalar | vector | matrix

Dependencies

B — Blue video stream scalar | vector | matrix

Dependencies

Pts — Shape coordinates M-by-3 matrix | M-by-4 matrix | M-by-2L

Dependencies

ROI — Region of interest four-element vector

Dependencies

Clr — Color of shape P-element vector | M-by-P matrix

Dependencies

Output

Port_1 — Output image scalar | vector | matrix

Parameters

Fill Shapes — Fill color off (default) | on

Fill color source — Source for fill color Specify via dialog (default) | Input port

Dependencies

Fill color — Shape fill color Black (default) | White | User-specified value

Dependencies

Border color source — Border color source (default) |

Dependencies

Border color — Border color Black (default) | White | User-specified value

Dependencies

Color value(s) — Color value color value | intensity value

Dependencies

Opacity factor (between 0 and 1) — Opacity factor value in the range [0,1] | R-element vector

Dependencies

Use antialiasing — Smoothing algorithm off | on

Dependencies

Image Signal — Image signal

Model Examples

Draw Rectangles on Image

Draw Circles on Image

Block Characteristics

Extended Capabilities

C/C++ Code Generation Generate C and C++ code using Simulink® Coder™.

Fixed-Point Conversion Design and simulate fixed-point systems using Fixed-Point Designer™.

Version History

See Also

`Image` — Input image
M-by-N matrix of intensity values | M-by-N-by-P color values

`R` — Red video stream
scalar | vector | matrix

`G` — Green video stream
scalar | vector | matrix

`B` — Blue video stream
scalar | vector | matrix

`Pts` — Shape coordinates
M-by-3 matrix | M-by-4 matrix | M-by-2L

`ROI` — Region of interest
four-element vector

`Clr` — Color of shape
P-element vector | M-by-P matrix

`Port_1` — Output image
scalar | vector | matrix

`Fill Shapes` — Fill color
off (default) | on

`Fill color source` — Source for fill color
`Specify via dialog` (default) | `Input port`

`Fill color` — Shape fill color
`Black` (default) | `White` | `User-specified value`

`Border color source` — Border color source
(default) |

`Border color` — Border color
`Black` (default) | `White` | `User-specified value`

`Color value(s)` — Color value
color value | intensity value

`Opacity factor (between 0 and 1)` — Opacity factor
value in the range [0,1] | R-element vector

`Use antialiasing` — Smoothing algorithm
off | on

`Image Signal` — Image signal

C/C++ Code Generation
Generate C and C++ code using Simulink® Coder™.

Fixed-Point Conversion
Design and simulate fixed-point systems using Fixed-Point Designer™.