qc_draw_text :: QUARC MATLAB Functions

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qc_draw_text

Draws text directly on an image rather than using a figure window or axes.

Syntax

im_out = qc_draw_text(im, font, text, r, c, ...) % Draw text on an image

Description

Draws text directly on an image. The output image will be a copy of the input image with the text drawn on it.

Parameters

A grayscale (HxW) or RGB (HxWx3) image as a uint8 array.

font

A structure defining the font to use. The structure has the following optional fields. If a field is omitted then a suitable default is used.

Field Name	Description
height	The height of the font in pixels.
width	The width of the font in pixels.
escapement	The escapement angle in degrees (may be fractional).
orientation	The orientation angle in degrees (may be fractional).
weight	The font weight (1.0 = normal, smaller is thinner, larger is bolder, 1.75 is standard bold, 2.5 is maximum weight).
italic	Whether to make the font italic (true or false).
underline	Whether to underline the font (true or false).
strikeout	Whether to strike out the font (true or false).
character_set	A string indicating the character set to use. Valid values are: 'default', 'ansi', 'baltic', 'chinesebig5', 'easteurope', 'gb2312', 'greek', 'hangul', 'mac', 'oem', 'russian', 'shiftjis', 'symbol', 'turkish', 'vietnamese', 'johab', 'arabic', 'hebrew', 'thai'.
output_precision	A string indicating the output precision. Valid values are: 'default', 'character', 'device', 'outline', 'ps_only', 'raster', 'string', 'stroke', 'tt_only', 'tt'.
clip_precision	A string indicating the clip precision. Valid values are: 'default', 'character', 'stroke'.
quality	A string indicating the quality. Valid values are: 'antialiased', 'cleartype', 'default', 'draft', 'nonantialiased', 'proof'.
pitch	A string indicating the pitch. Valid values are: 'default', 'fixed', 'variable'.
family	A string indicating the family. Valid values are: 'decorative', 'dontcare', 'modern', 'script', 'swiss'.
face	A string containing the name of the font face to use e.g. 'Times New Roman'.

text

A string containing the text to draw.

The row in pixels at which to place the origin of the text drawn.

The column in pixels at which to place the origin of the text drawn.

The function may take additional property/value pairs as arguments. Valid properties are:

Property	Description
'horizontal-align'	The horizontal alignment of the text relative to the (r,c) position. Valid values are: 'left', 'center', 'right'.
'vertical-align'	The vertical alignment of the text relative to the (r,c) position. Valid values are: 'bottom', 'baseline', 'top'.
'color'	The foreground color of the text. The value is a 3-vector containing the red, green and blue components i.e. [red, green, blue] where each component must lie in the range 0 to 255.
'background-color'	The background color of the text. The value is a 3-vector containing the red, green and blue components i.e. [red, green, blue] where each component must lie in the range 0 to 255. If no background color is specified then the background is transparent.

Outputs

im_out

The output image with the text drawn on it. It will have the same dimensions as the input image.

Examples

im = imread(fullfile(qc_root, 'blocks', 'command_prompt.jpg'));
font.height = 20; % make text 20 pixels high
im_out = qc_draw_text(im, font, 'Hello world', size(im,1)/2, size(im,2)/2, 'horizontal-align', 'center', 'color', [255 255 0]); % Draw centered yellow text
imshow(im_out);

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