ossimOpenCVSobelFilter Class Reference

OpenCV Sobel Filter. More...

#include <ossimOpenCVSobelFilter.h>

Public Member Functions
	ossimOpenCVSobelFilter (ossimObject *owner=NULL)
	ossimOpenCVSobelFilter (ossimImageSource *inputSource, int xorder=1, int yorder=1, int aperture_size=3)
	ossimOpenCVSobelFilter (ossimObject owner, ossimImageSource inputSource, int xorder=1, int yorder=1, int aperture_size=3)
ossimString	getShortName () const
ossimString	getLongName () const
virtual ossimRefPtr < ossimImageData >	getTile (const ossimIrect &tileRect, ossim_uint32 resLevel=0)
virtual void	initialize ()
virtual ossimScalarType	getOutputScalarType () const
ossim_uint32	getNumberOfOutputBands () const
virtual bool	saveState (ossimKeywordlist &kwl, const char *prefix=0) const
virtual bool	loadState (const ossimKeywordlist &kwl, const char *prefix=0)
Protected Member Functions
void	runUcharTransformation (ossimImageData *tile)
Protected Attributes
ossimRefPtr< ossimImageData >	theTile
	Output tile.
int	theXOrder
	Order of the derivative of x.
int	theYOrder
	Order of the derivative of y.
int	theApertureSize
	Size of the extended Soble kernel, must be 1, 3, 5 or 7.

Detailed Description

OpenCV Sobel Filter.

Calculates the first, second, third or mixed image derivatives using an extended Sobel operator.

Parameters:

	xorder	Order of the derivative x
	yorder	Order of the derivative y
	aperture_size	Size of the extended Sobel kernel, must be 1, 3, 5 or 7

In all cases except 1, an $\texttt{apertureSize} \times \texttt{apertureSize}$ separable kernel will be used to calculate the derivative. For $\texttt{apertureSize} = 1$ a $3 \times 1$ or $1 \times 3$ a kernel is used (Gaussian smoothing is not done). There is also the special value CV_SCHARR (-1) that corresponds to a $3\times 3$ Scharr filter that may give more accurate results than a $3\times 3$ Sobel. Scharr aperture is

$\vecthreethree {-3}{0}{3} {-10}{0}{10} {-3}{0}{3}$

for the x-derivative or transposed for the y-derivative.

The function calculates the image derivative by convolving the image with the appropriate kernel:

$\texttt{dst}(x,y) = \frac{d^{xorder+yorder}}{dx^{xorder} \cdot dy^{yorder}} \texttt{src}$

The Sobel operators combine Gaussian smoothing and differentiation so the result is more or less resistant to the noise. Most often, the function is called with (xorder = 1, yorder = 0, apertureSize = 3) or (xorder = 0, yorder = 1, apertureSize = 3) to calculate the first x- or y- image derivative. The first case corresponds to a kernel of:

$\left[ \begin{array}{ccc} -1 & 0 & 1 \\ -2 & 0 & 2 \\ 1 & 2 & 1 \\ \end{array} \right]$

and the second one corresponds to a kernel of:

$\left[ \begin{array}{ccc} -1 & -2 & -1 \\ 0 & 0 & 0 \\ 1 & 2 & 1 \\ \end{array} \right]$

or a kernel of:

$\left[ \begin{array}{ccc} 1 & 2 & 1 \\ 0 & 0 & 0 \\ -1 & -2 & -1 \\ \end{array} \right]$

depending on the image origin (origin field of IplImage structure). Besides 8-bit images the function can process 32-bit floating-point images. Both the source and the destination must be single-channel images of equal size or equal ROI size.

Member Function Documentation

bool ossimOpenCVSobelFilter::loadState	(	const ossimKeywordlist &	kwl,
		const char *	prefix = `0`
	)			`[virtual]`

Method to the load (recreate) the state of an object from a keyword list. Return true if ok or false on error.

The documentation for this class was generated from the following files:

ossimOpenCVSobelFilter.h
ossimOpenCVSobelFilter.cpp

ossimOpenCVSobelFilter Class Reference

Public Member Functions

Protected Member Functions

Protected Attributes

Detailed Description

Member Function Documentation