Integral Image Operations

---

Methods for computing and dealing with Integral Images

See also:

Image Math Operations

Image macros to facilitate promotion of pixel types

Functions
template<typename promo = int, typename srcType , typename dstType = typename nrt::promote<srcType, promo>::type>
nrt::Image< nrt::PixGray < dstType > >	nrt::getIntegralImage (nrt::Image< nrt::PixGray< srcType > > const im)
	Generate an Integral Image from a grayscale Image.
template<typename promo = int, typename srcType , typename dstType = typename nrt::promote<srcType, promo>::type>
nrt::Image< nrt::PixGray < dstType > >	nrt::getIntegralImage (nrt::Image< nrt::PixGray< srcType > > const im, std::function< dstType(srcType const &)> evalFxn)
	Generate an Integral Image from a grayscale Image.
template<typename promo = int, typename srcType , typename dstType = typename nrt::promote<srcType, promo>::type>
dstType	nrt::getIIValue (nrt::Image< nrt::PixGray< srcType >> integralImage, nrt::Rectangle< nrt::int32 > rect)
	Compute the sum of values inside a rectangular region of an Image using an Integral Image.

---

Function Documentation

template<typename promo = int, typename srcType , typename dstType = typename nrt::promote<srcType, promo>::type>

nrt::Image<nrt::PixGray<dstType> > nrt::getIntegralImage

(

nrt::Image< nrt::PixGray< srcType > > const

im

)

Generate an Integral Image from a grayscale Image.

This function returns the integral image of the input image which contains a single-valued (PixGray) value It is useful for efficiently calculating the sum of values within a rectanglular region of an Image.

template<typename promo = int, typename srcType , typename dstType = typename nrt::promote<srcType, promo>::type>

dstType nrt::getIIValue	(	nrt::Image< nrt::PixGray< srcType >>	integralImage,
		nrt::Rectangle< nrt::int32 >	rect
	)

Compute the sum of values inside a rectangular region of an Image using an Integral Image.

After an Integral Image has been computed for a source Image, this method can use that Integral Image to compute the sum of pixel values inside a rectangular region of that source Image very efficiently using its Integral Image.

Parameters:

integralImage	The Integral Image computed via getIntegralImage().
rect	The rectangular region for which you want to compute the sum.

Definition at line 70 of file IntegralOpsImpl.H.

References nrt::Rectangle< T >::bottomLeftI(), nrt::Rectangle< T >::bottomRightI(), nrt::Rectangle< T >::topLeft(), and nrt::Rectangle< T >::topRightI().