CopySubpixIntersect

Syntax

Parameters

pSrc	Pointer to the source image ROI.
srcStep	Distance in bytes between starts of consecutive lines in the source image.
srcRoiSize	Size of the source image ROI in pixels.
pDst	Pointer to the destination image ROI.
dstStep	Distance in bytes between starts of consecutive lines in the source and destination image.
dstRoiSize	Size of the destination ROI in pixels.
point	Center point of the window.
pMin	Pointer to coordinates of the top left pixel of the intersection in the destination image.
pMax	Pointer to coordinates of the bottom right pixel of the intersection in the destination image.
scaleFactor	Scale factor (see Integer Result Scaling).

Description

The function ippiCopySubpixIntersect is declared in the ippcv.h file. It operates with ROI (see Regions of Interest in Intel IPP).

This function determines the intersection of the source image and the window of size dstRoiSize centered in point point. The corresponding pixels of the destination image are calculated using linear interpolation (see Linear Interpolation in Appendix B) in accordance with the following formula:

where Xsubpix(j) = min(max(point.x + j - 0.5*(dstRoiSize.width - 1), 0), srcRoiSize.width - 1),

Ysubpix(i) = min(max(point.y + i - 0.5*(dstRoiSize.height - 1), 0), srcRoiSize.height - 1),

i = 0, ... dstRoiSize.height - 1 , j = 0, ... dstRoiSize.width - 1 .

Minimal values of j and i (coordinates of the top left calculated destination pixel) are assigned to pMin.x and pMin.y, maximal values (coordinates of the top left calculated destination pixel) - to pMin.x and pMin.y. (See Figure Image Copying with Subpixel Precision Using ippiCopySubpixIntersect Function.)

Example “Using ippiCopySubpixIntersect” shows how to use the function ippiCopySubpixIntersect_8u_C1R.

The height (width) of the destination ROI cannot be less than the sum of the height (width) of source ROI and the topBorderHeight (leftBorderWidth) parameter.

Return Values

ippStsNoErr	Indicates no error. Any other value indicates an error or a warning.
ippStsNullPtrErr	Indicates an error when any of the specified pointers is NULL.
ippStsSizeErr	Indicates an error condition if srcRoiSize or dstRoiSize has a field with a zero or negative value.
ippStsStepErr	Indicates an error condition if srcStep is less than srcRoiSize.width * <pixelSize>, or dstStep is less than dstRoiSize.width * <pixelSize>.

Using ippiCopySubpixIntersect

Ipp8u src[8*6] = {
      7, 7, 6, 6, 6, 6, 7, 7,
      6, 5, 5, 5, 5, 5, 5, 6,
      6, 5, 4, 3, 3, 4, 5, 6,
      6, 5, 4, 3, 3, 4, 5, 6,
      6, 5, 5, 5, 5, 5, 5, 6,
      6, 6, 6, 6, 6, 6, 6, 6
    };
Ipp8u dst[7*4];
IppiSize srcRoi = { 8, 6 };
IppiSize dstRoi = { 7, 4 };
IppiPoint_32f point = { 4, 1 };
IppiPoint min;
IppiPoint max;
		
ippiCopySubpixIntersect_8u_C1R (src, 8, srcRoi, dst, 7, dstRoi, point, &min, &max );

		Results
source image:
7 7 6 6 6 6 7 7
6 5 5 5 5 5 5 6
6 5 4 3 3 4 5 6
6 5 4 3 3 4 5 6
6 5 5 5 5 5 5 6
6 6 6 6 6 6 6 6
		
destination image:
7 6 6 6 6 7 7
6 6 6 6 6 6 7
5 5 4 4 5 5 6
5 4 3 3 4 5 6
		
min = { 0, 1 }
max = { 5, 3 }