Extended Image Processing

Modules
	Structured forests for fast edge detection
	Filters
	Superpixels
	Image segmentation
	Fast line detector

Functions
void	cv::ximgproc::niBlackThreshold (InputArray _src, OutputArray _dst, double maxValue, int type, int blockSize, double delta)
	Applies Niblack thresholding to input image. More...
void	cv::ximgproc::thinning (InputArray src, OutputArray dst, int thinningType=THINNING_ZHANGSUEN)
	Applies a binary blob thinning operation, to achieve a skeletization of the input image. More...

Detailed Description

Function Documentation

niBlackThreshold()

void cv::ximgproc::niBlackThreshold	(	InputArray	_src,
		OutputArray	_dst,
		double	maxValue,
		int	type,
		int	blockSize,
		double	delta
	)

Applies Niblack thresholding to input image.

The function transforms a grayscale image to a binary image according to the formulae:

• THRESH_BINARY

  \[dst(x,y) = \fork{\texttt{maxValue}}{if \(src(x,y) > T(x,y)\)}{0}{otherwise}\]

• THRESH_BINARY_INV

  \[dst(x,y) = \fork{0}{if \(src(x,y) > T(x,y)\)}{\texttt{maxValue}}{otherwise}\]

  where \(T(x,y)\) is a threshold calculated individually for each pixel.

The threshold value \(T(x, y)\) is the mean minus \( delta \) times standard deviation of \(\texttt{blockSize} \times\texttt{blockSize}\) neighborhood of \((x, y)\).

The function can't process the image in-place.

Parameters

_src	Source 8-bit single-channel image.
_dst	Destination image of the same size and the same type as src.
maxValue	Non-zero value assigned to the pixels for which the condition is satisfied, used with the THRESH_BINARY and THRESH_BINARY_INV thresholding types.
type	Thresholding type, see cv::ThresholdTypes.
blockSize	Size of a pixel neighborhood that is used to calculate a threshold value for the pixel: 3, 5, 7, and so on.
delta	Constant multiplied with the standard deviation and subtracted from the mean. Normally, it is taken to be a real number between 0 and 1.

See also

threshold, adaptiveThreshold

thinning()

void cv::ximgproc::thinning	(	InputArray	src,
		OutputArray	dst,
		int	thinningType = THINNING_ZHANGSUEN
	)

Applies a binary blob thinning operation, to achieve a skeletization of the input image.

The function transforms a binary blob image into a skeletized form using the technique of Zhang-Suen.

Parameters

src	Source 8-bit single-channel image, containing binary blobs, with blobs having 255 pixel values.
dst	Destination image of the same size and the same type as src. The function can work in-place.
thinningType	Value that defines which thinning algorithm should be used. See cv::ThinningTypes