Drawing Functions#

Detailed Description#

Drawing functions work with matrices/images of arbitrary depth. The boundaries of the shapes can be rendered with antialiasing (implemented only for 8-bit images for now). All the functions include the parameter color that uses an RGB value (that may be constructed with the Scalar constructor ) for color images and brightness for grayscale images. For color images, the channel ordering is normally Blue, Green, Red. This is what imshow, imread, and imwrite expect. So, if you form a color using the Scalar constructor, it should look like:

\[ \texttt{Scalar} (blue \_ component, green \_ component, red \_ component[, alpha \_ component]) \]

If you are using your own image rendering and I/O functions, you can use any channel ordering. The drawing functions process each channel independently and do not depend on the channel order or even on the used color space. The whole image can be converted from BGR to RGB or to a different color space using cvtColor .

If a drawn figure is partially or completely outside the image, the drawing functions clip it. Also, many drawing functions can handle pixel coordinates specified with sub-pixel accuracy. This means that the coordinates can be passed as fixed-point numbers encoded as integers. The number of fractional bits is specified by the shift parameter and the real point coordinates are calculated as \(\texttt{Point}(x,y)\rightarrow\texttt{Point2f}(x*2^{-shift},y*2^{-shift})\) . This feature is especially effective when rendering antialiased shapes.

Note

The functions do not support alpha-transparency when the target image is 4-channel. In this case, the color[3] is simply copied to the repainted pixels. Thus, if you want to paint semi-transparent shapes, you can paint them in a separate buffer and then blend it with the main image.

Classes#

Name	Description
`class` `cv::FontFace`	Wrapper on top of a truetype/opentype/etc font, i.e. Freetype’s FT_Face. View details
`class` `cv::LineIterator`	Class for iterating over all pixels on a raster line segment. View details

Enumerations#

enum cv::HersheyFonts {
    cv::FONT_HERSHEY_SIMPLEX = 0,
    cv::FONT_HERSHEY_PLAIN = 1,
    cv::FONT_HERSHEY_DUPLEX = 2,
    cv::FONT_HERSHEY_COMPLEX = 3,
    cv::FONT_HERSHEY_TRIPLEX = 4,
    cv::FONT_HERSHEY_COMPLEX_SMALL = 5,
    cv::FONT_HERSHEY_SCRIPT_SIMPLEX = 6,
    cv::FONT_HERSHEY_SCRIPT_COMPLEX = 7,
    cv::FONT_ITALIC = 16
}

View details

enum cv::LineTypes {
    cv::FILLED = -1,
    cv::LINE_4 = 4,
    cv::LINE_8 = 8,
    cv::LINE_AA = 16
}

View details

enum cv::MarkerTypes {
    cv::MARKER_CROSS = 0,
    cv::MARKER_TILTED_CROSS = 1,
    cv::MARKER_STAR = 2,
    cv::MARKER_DIAMOND = 3,
    cv::MARKER_SQUARE = 4,
    cv::MARKER_TRIANGLE_UP = 5,
    cv::MARKER_TRIANGLE_DOWN = 6
}

View details

enum cv::PutTextFlags {
    cv::PUT_TEXT_ALIGN_LEFT =0,
    cv::PUT_TEXT_ALIGN_CENTER =1,
    cv::PUT_TEXT_ALIGN_RIGHT =2,
    cv::PUT_TEXT_ALIGN_MASK =3,
    cv::PUT_TEXT_ORIGIN_TL =0,
    cv::PUT_TEXT_ORIGIN_BL =32,
    cv::PUT_TEXT_WRAP =128
}

Defines various put text flags. View details

`FONT_HERSHEY_SIMPLEX` Python: `cv.FONT_HERSHEY_SIMPLEX`	normal size sans-serif font
`FONT_HERSHEY_PLAIN` Python: `cv.FONT_HERSHEY_PLAIN`	small size sans-serif font
`FONT_HERSHEY_DUPLEX` Python: `cv.FONT_HERSHEY_DUPLEX`	normal size sans-serif font (more complex than FONT_HERSHEY_SIMPLEX)
`FONT_HERSHEY_COMPLEX` Python: `cv.FONT_HERSHEY_COMPLEX`	normal size serif font
`FONT_HERSHEY_TRIPLEX` Python: `cv.FONT_HERSHEY_TRIPLEX`	normal size serif font (more complex than FONT_HERSHEY_COMPLEX)
`FONT_HERSHEY_COMPLEX_SMALL` Python: `cv.FONT_HERSHEY_COMPLEX_SMALL`	smaller version of FONT_HERSHEY_COMPLEX
`FONT_HERSHEY_SCRIPT_SIMPLEX` Python: `cv.FONT_HERSHEY_SCRIPT_SIMPLEX`	hand-writing style font
`FONT_HERSHEY_SCRIPT_COMPLEX` Python: `cv.FONT_HERSHEY_SCRIPT_COMPLEX`	more complex variant of FONT_HERSHEY_SCRIPT_SIMPLEX
`FONT_ITALIC` Python: `cv.FONT_ITALIC`	flag for italic font

`FILLED` Python: `cv.FILLED`
`LINE_4` Python: `cv.LINE_4`	4-connected line
`LINE_8` Python: `cv.LINE_8`	8-connected line
`LINE_AA` Python: `cv.LINE_AA`	antialiased line

`MARKER_CROSS` Python: `cv.MARKER_CROSS`	A crosshair marker shape.
`MARKER_TILTED_CROSS` Python: `cv.MARKER_TILTED_CROSS`	A 45 degree tilted crosshair marker shape.
`MARKER_STAR` Python: `cv.MARKER_STAR`	A star marker shape, combination of cross and tilted cross.
`MARKER_DIAMOND` Python: `cv.MARKER_DIAMOND`	A diamond marker shape.
`MARKER_SQUARE` Python: `cv.MARKER_SQUARE`	A square marker shape.
`MARKER_TRIANGLE_UP` Python: `cv.MARKER_TRIANGLE_UP`	An upwards pointing triangle marker shape.
`MARKER_TRIANGLE_DOWN` Python: `cv.MARKER_TRIANGLE_DOWN`	A downwards pointing triangle marker shape.

Drawing Functions#

Detailed Description#

Classes#

Enumerations#

Enumeration Type Documentation#

HersheyFonts#

LineTypes#

MarkerTypes#

PutTextFlags#

Function Documentation#

arrowedLine()#

circle()#

clipLine()#

clipLine()#

clipLine()#

drawContours()#

drawFrameAxes()#

drawMarker()#

ellipse()#

ellipse()#

ellipse2Poly()#

ellipse2Poly()#

fillConvexPoly()#

fillConvexPoly()#

fillPoly()#

fillPoly()#

getFontScaleFromHeight()#

getTextSize()#

getTextSize()#

line()#

polylines()#

polylines()#

putText()#

putText()#

rectangle()#

rectangle()#

Macro Definition Documentation#

CV_RGB#