insertObjectAnnotation

Annotate truecolor or grayscale image or video stream

Syntax

RGB = insertObjectAnnotation(I,shape,position,label)

RGB = insertObjectAnnotation(I,shape,position,label,Name,Value)

insertObjectAnnotation(I,'rectangle',position,label)

insertObjectAnnotation(I,'circle',position,label)

Description

RGB = insertObjectAnnotation(I,shape,position,label) returns a truecolor image annotated with shape and label at the location specified by position.

RGB = insertObjectAnnotation(I,shape,position,label,Name,Value) uses additional options specified by one or more Name,Value pair arguments.

insertObjectAnnotation(I,'rectangle',position,label) inserts rectangles and labels at the location indicated by the position matrix.

insertObjectAnnotation(I,'circle',position,label) inserts circles and corresponding labels at the location indicated by the position matrix.

Examples

Annotate Image with Numbers and Strings

Read image.

I = imread('board.tif');

Create labels of floating point numbers. The floating point numbers relate to confidence value labels.

label_str = cell(3,1);
conf_val = [85.212 98.76 78.342];
for ii=1:3
    label_str{ii} = ['Confidence: ' num2str(conf_val(ii),'%0.2f') '%'];
end

Set the position for the rectangles as [x y width height].

   position = [23 373 60 66;35 185 77 81;77 107 59 26];

Insert the labels.

RGB = insertObjectAnnotation(I,'rectangle',position,label_str,...
    'TextBoxOpacity',0.9,'FontSize',18);

Display the annotated image.

figure
imshow(RGB)
title('Annotated chips');

Annotate Image with Integer Numbers

Read image.

I = imread('coins.png');

Set positions for the circles. The first two values represents the center at (x,y) and the third value is the radius.

position = [96 146 31;236 173 26];

Set the label to display the integers 5 and 10 (U.S. cents).

label = [5 10];

Insert the annotations.

RGB = insertObjectAnnotation(I,'circle',position,label,'LineWidth',3,'Color',{'cyan','yellow'},'TextColor','black');

Display.

figure
imshow(RGB)
title('Annotated coins');

Input Arguments

I — Truecolor or grayscale image

M-by-N-by-3 truecolor | M-by-N 2-D grayscale image

Truecolor or grayscale image, specified as an image or video stream. The input image can be either an M-by-N-by-3 truecolor or a M-by-N 2-D grayscale image.

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

shape — Rectangle or circle annotation

‘rectangle’ | ‘circle’

Rectangle or circle annotation, specified as a character vector indicating the annotation shape.

Data Types: char

position — Location and size of the annotation shape

M-by-3 matrix | M-by-4 matrix

Location and size of the annotation shape, specified as an M-by-3 or M-by-4 matrix. When you specify a rectangle, the position input matrix must be an M-by-4 matrix. Each row, M, specifies a rectangle as a four-element vector, [x y width height]. The elements, x and y, indicate the upper-left corner of the rectangle, and the width and height specify the size.

When you specify a circle, the position input matrix must be an M-by-3 matrix, where each row, M, specifies a three-element vector [x y r]. The elements, x and y, indicate the center of the circle and r specifies the radius.

Example: position = [50 120 75 75]

A rectangle with top-left corner located at x=50, y=120, with a width and height of 75 pixels.

Example: position = [96 146 31]

A circle with center located at x=96, y=146 and a radius of 31 pixels.

Example: position = [23 373 60 66;35 185 77 81;77 107 59 26]

Location and size for three rectangles.

label — Label to associate with a shape

M-element numeric vector | string | categorical labels | cell array of ASCII character vectors

Label to associate with a shape, specified as an M numeric vector, string, categorical labels, or a cell array of ASCII character vectors. The character, string, or categorical labels must be encoded as ASCII characters. The cell array must be the of length equal to the number of shape positions. You can specify a scalar label for all shapes as a numeric scalar, string, or categorical.

Example: label = [5 10], where the function marks the first shape with the label, 5, and the second shape with the label, 10.

Name-Value 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.

Example: 'Color', 'white' sets the color for the label text box to white.

Font — Font face of text

'LucidaSansRegular' (default) | character vector | string scalar

Font face of text, specified as the comma-separated pair consisting of 'Font' and a character vector. The font face must be one of the available truetype fonts installed on your system. To get a list of available fonts on your system, type listTrueTypeFonts at the MATLAB^® command prompt.

Data Types: char

FontSize — Label text font size

12 (default) | integer in the range of [8 72]

Label text font size, specified as the comma-separated pair consisting of 'FontSize' and an integer corresponding to points in the range of [8 72].

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

LineWidth — Shape border line width

1 (default)

Shape border line width, specified as the comma-separated pair consisting of 'LineWidth' and a positive scalar integer in pixels.

Color — Color for shape and corresponding label text box

'yellow' (default) | character vector | string scalar | [R G B] vector | cell array | string array | M-by-3 matrix

Color for shape and for corresponding label text box, specified as the comma-separated pair consisting of 'Color' and either a character vector, an [R G B] vector, a cell array, or an M-by-3 matrix.

To specify one color for all shapes, set this parameter to either a character vector or an [R G B] vector. To specify a color for each of the M shapes, set this parameter to a cell array of M character vectors. Alternatively, you can specify an M-by-3 matrix of RGB values for each annotation. RGB values must be in the range of the input image data type.

Supported colors: 'blue', 'green', 'cyan', 'red', 'magenta', 'black', and 'white'.

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

TextColor — Color of text in text label

'black' (default) | character vector | string scalar | [R G B] vector | cell array | string array | M-by-3 matrix

Color of text in text label, specified as the comma-separated pair consisting of 'TextColor' and either a character vector, an [R G B] vector, a cell array, or an M-by-3 matrix. To specify one color for all text, set this parameter to either a character vector or an [R G B] vector. To specify a color for each of the M text labels, set this parameter to a cell array of M character vectors. Alternatively, you can specify an M-by-3 matrix of RGB values for each annotation. RGB values must be in the range of the input image data type.

Supported colors: 'blue', 'green', 'cyan', 'red', 'magenta', 'yellow', and 'white'.

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

TextBoxOpacity — Opacity of text label box background

0.6 (default) | range of [0 1]

Opacity of text label box background, specified as the comma-separated pair consisting of 'TextBoxOpacity' and a scalar defining the opacity of the background of the label text box. Specify this value in the range of 0 to 1.

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

Output Arguments

RGB — Truecolor or grayscale image with annotation

M-by-N-by-3 truecolor

Truecolor image with annotation, returned as an image or video stream.

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

Extended Capabilities

C/C++ Code Generation

Generate C and C++ code using MATLAB® Coder™.

Usage notes and limitations:

• Input image must be bounded. See Specify Upper Bounds for Variable-Size Arrays (MATLAB Coder).

• See System Objects in MATLAB Code Generation (MATLAB Coder).