Include Files

Domain Dependencies

Headers:

ippcore.h

,

ippvm.h

,

ipps.h

Libraries:

ippcore.lib

,

ippvm.lib

,

ipps.lib

Description

This function transforms the source image pixel coordinates (

x

,

y

) according to the following formulas:

x

' = (

c

00

*

x

+

c

01

*

y

+

c

02

)/ (

c

20

*

x

+

c

21

*

y

+

c

22

)

y

' = (

c

10

*

x

+

c

11

*

y

+

c

12

)/(

c

20

*

x

+

c

21

*

y

+

c

22

)

where

The

ippiWarpPerspectiveCubic

function operates with ROI (see Regions of Interest in Intel IPP). The transformed part of the source image is resampled with the cubic interpolation method and stored in the destination image ROI. You need to define the destination image ROI origin by the following parameters: the offset of the destination ROI with respect to the destination image origin and the destination image ROI size. The parameter

pDst

must point to the processed destination image ROI.

If you initialize the warp specification structure using the

ippiWarpPerspectiveCubicInit

function, you can specify the source image ROI in the following ways:

Set the
srcRoi
value to
ippRectInfinite
, which means that the ROI is not specified. In this case,
pSrc
must point to the processed source image. Pixels that are outside the source image boundaries are computed according to the specified border type.
Set the
srcRoi
value to the part of the processed source image. In this case,
pSrc
must point to the processed source image ROI. The operations take place only inside the specified region of interest
srcRoi
. It means that the destination image pixels mapped to the outer pixels of the specified source image region are not changed.

If you initialize the warp specification structure using the

ippiWarpQuadCubicInit

function, set the

pSrc

value to the processed source image. The operations take place only inside the source quadrangle

srcQuad

that is specified in the

ippiWarpQuadCubicInit

function.

To specify the algorithm for borders processing, set the

borderType

and

pBorderValue

parameters when initializing the

IppiWarpSpec

structure. The data type of

pBorderValue

is automatically converted from

Ipp64f

to the data type of the processed images. The function supports the following algorithms for borders processing:

If the border type is equal to
ippBorderRepl
, the source image outer pixels are replicated from the edge pixels.
If the border type is equal to
ippBorderConst
, the outer pixels are set to the constant value specified in
pBorderValue
.
If the border type is equal to
ippBorderTransp
, destination image pixels mapped to the outer source image pixels are not changed. The outer pixels required for cubic interpolation are replicated from the edge pixels.
If the border type is equal to
ippBorderInMem
, destination image pixels mapped to the outer source image pixels are not changed. The outer pixels required for cubic interpolation are obtained from the out of the source image origin space. Cubic interpolation requires additional one-pixel edge from each source image side.
The mixed border types can be obtained by the bitwise operation
OR
between
ippBorderTransp
and the
ippBorderInMemTop
,
ippBorderInMemBottom
,
ippBorderInMemLeft
,
ippBorderInMemRight
values

Before using the

ippiWarpPerspectiveCubic

function, you need to initialize the

IppiWarpSpec

structure using the

ippiWarpPerspectiveCubicInit

function and compute the size of the external buffer

pBuffer

using the

ippiWarpGetBufferSize

function.

To compute the perspective transform parameters, use the

ippiGetPerspectiveQuad

,

ippiGetPerspectiveBound

, and

ippiGetPerspectiveTransform

functions.

For an example on how to use this functionality, refer to the example provided with the

ippiWarpPerspectiveNearest

function description.