insertMarker

Insert markers in image or video

Syntax

RGB = insertMarker(I,position)

RGB = insertMarker(I,position,marker)

RGB = insertMarker(___,Name=Value)

Description

RGB = insertMarker(I,position) insert plus (+) markers into the truecolor or grayscale image I. The function draws markers by overwriting pixel values at the specified positions. The output image RGB is always a truecolor image.

example

RGB = insertMarker(I,position,marker) inserts markers of the specified marker type marker.

RGB = insertMarker(___,Name=Value) specifies options using one or more name-value arguments in addition to any combination of input arguments from previous syntaxes. For example, MarkerColor="red" specifies to render the inserted position markers in red.

Examples

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Draw Markers on an Image

Open Live Script

Read an image into the workspace.

I = imread("peppers.png");

Insert a plus (+) marker onto the image at specified position.

RGB = insertMarker(I,[147 279]);

Specify the positions, colors, and sizes of four cross (x) markers and insert onto the image.

pos = [120 248; 195 246; 195 312; 120 312];
color = {"red","white","green","magenta"};
RGB = insertMarker(RGB,pos,"x",MarkerColor=color,Size=10);

Display the image.

imshow(RGB)

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

Input Arguments

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`I` — Input image
M-by-N-by-3 truecolor image | M-by-N grayscale image

Input image, specified as an M-by-N-by-3 truecolor or an M-by-N grayscale image.

Data Types: single | double | int16 | uint8 | uint16

`position` — Position of markers
M-by-2 matrix | M-element vector of points objects

Position of markers, specified as an M-by-2 matrix, where each row is an image coordinate pair of the form [x y], or an M-element vector of one of the points objects listed on the Point Feature Types page. M is the number of markers to insert into the image. The function defines the position of each marker as the [x y] pair of coordinates in the matrix, as the value of the Location property of the corresponding point feature object.

`marker` — Type of marker
`"plus"` (default) | character vector | string scalar

Type of marker, specified as a character vector or string scalar. You can specify the marker type using either the full text name or the corresponding symbol.

Full Text Name	Symbol
`"circle"`	`"o"`
`"x-mark"`	`"x"`
`"plus"`	`"+"`
`"star"`	`"*"`
`"square"`	`"s"`

Data Types: char | string

Name-Value Arguments

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Specify optional pairs of arguments as Name1=Value1,...,NameN=ValueN, where Name is the argument name and Value is the corresponding value. Name-value arguments must appear after other arguments, but the order of the pairs does not matter.

Example: insertMarker(I,position,Color="yellow") sets the marker color to yellow.

Before R2021a, use commas to separate each name and value, and enclose Name in quotes.

Example: insertMarker(I,position,"Color","yellow") sets the marker color to yellow.

`Size` — Size of marker
`3` (default) | scalar

Size of the marker in pixels, specified as a scalar in the range [1,Inf).

`MarkerColor` — Marker color
`"green"` (default) | short color name | color name | vector of color names | three-column matrix of RGB triplets

Marker color, specified as a short color name, color name, vector of color names, three-column matrix of RGB triplets.

The supported colors table lists RGB intensities in the range [0, 1], but you must specify RGB triplets in the range of your selected data type. For example, if specifying this argument as a matrix of uint8 values, you must convert each intensity value to the range [0, 255]. To convert the listed intensity values to a uint8 data type, use the code uint8(255*intensity), where intensity is an RGB triplet value listed in the table.

You can specify a different color for each marker or one color for all markers. To specify one color for all markers, specify MarkerColor as a color name or an [R G B] vector.

Specification	Format	Example
Specify one color for all shapes (or markers)	Short color name or color name	`"r"` `"red"`
Specify one color for all shapes (or markers)	RGB triplet	`[1 0 0]`
Specify a color for each shape (or marker)	Vector of color names	`["red","yellow","blue"]`
Specify a color for each shape (or marker)	Three-column matrix of RGB triplets	[1 0 0 0 1 1 1 0 1 1 1 1]

This table lists the supported marker colors.

Color Name	Short Name	RGB Triplet
`"red"`	`"r"`	`[1 0 0]`
`"green"`	`"g"`	`[0 1 0]`
`"blue"`	`"b"`	`[0 0 1]`
`"cyan"`	`"c"`	`[0 1 1]`
`"magenta"`	`"m"`	`[1 0 1]`
`"yellow"`	`"y"`	`[1 1 0]`
`"black"`	`"k"`	`[0 0 0]`
`"white"`	`"w"`	`[1 1 1]`