Functions
I32	fourpoint_calculate (point p0, point p1, point p2, point p3, point q0, point q1, point q2, point q3, F32 **a)
	Calculates the Inverse Homography Transformation Matrix for 2×4 Coordinate Points. More...

I32	homography_image_transform (image src, image dst, F32 a[3][3], U8 bgnd)
	Subpixel Interpolated Homography Transformation of an Image. More...

Detailed Description

Function Documentation

◆ fourpoint_calculate()

I32 fourpoint_calculate	(	point *	p0,
		point *	p1,
		point *	p2,
		point *	p3,
		point *	q0,
		point *	q1,
		point *	q2,
		point *	q3,
		float **	a
	)

The function calculates the inverse homography transformation matrix from sample point mappings given: Input to the function are four known points in the original coordinate system and their image points in the transformed coordinate system.

See also: Bernd Jaehne, practical handbook on image processing for scientific applications pp 268-270.

Parameters

[in]	p0,p1,p2,p3	Sample Point Positions before Transformation.
[in]	q0,q1,q2,q3	Sample Point Positions after Transformation.
[out]	a	Inverse 2D Transformation Matrix 3×3.

Returns: Standard Error Code.

Return values

ERR_MEMORY	if Memory Allocation Fails.
ERR_SINGULAR	if Point Selection is Inappropriate.
ERR_NONE	on Success.

◆ homography_image_transform()

I32 homography_image_transform	(	image *	src,
		image *	dst,
		float	a[3][3],
		U8	bgnd
	)

This function performs a subpixel interpolated homography transformation to an image using the inverse homography matrix, e.g. returned by fourpoint_calculate(). Be aware that the inverse transformation matrix is required.