Warp Perspective

Detailed Description

Performs a perspective transform on an image.

This kernel performs an perspective transform with a 3x3 Matrix \( M \) with this method of pixel coordinate translation:

\begin{eqnarray} x0 &=& M_{1,1}*x + M_{1,2}*y + M_{1,3} \\ y0 &=& M_{2,1}*x + M_{2,2}*y + M_{2,3} \\ z0 &=& M_{3,1}*x + M_{3,2}*y + M_{3,3} \\ output(x,y) &=& input(\frac{x0}{z0},\frac{y0}{z0}) \end{eqnarray}

This translates into the C declaration:

    // x0 = a x + b y + c;
    // y0 = d x + e y + f;
    // z0 = g x + h y + i;
    vx_float32 mat[3][3] = {
        {a, d, g}, // 'x' coefficients
        {b, e, h}, // 'y' coefficients
        {c, f, i}, // 'offsets'
    };
    vx_matrix matrix = vxCreateMatrix(context, VX_TYPE_FLOAT32, 3, 3);
    vxAccessMatrix(matrix, NULL);
    vxCommitMatrix(matrix, mat);

Functions
vx_status	vxuWarpPerspective (vx_context context, vx_image input, vx_matrix matrix, vx_enum type, vx_image output)
	[Immediate] Performs an Perspective warp on an image. More...
vx_node	vxWarpPerspectiveNode (vx_graph graph, vx_image input, vx_matrix matrix, vx_enum type, vx_image output)
	[Graph] Creates a Perspective Warp Node. More...

Function Documentation

vx_node vxWarpPerspectiveNode	(	vx_graph	graph,
		vx_image	input,
		vx_matrix	matrix,
		vx_enum	type,
		vx_image	output
	)

[Graph] Creates a Perspective Warp Node.

Parameters

[in]	graph	The reference to the graph.
[in]	input	The input VX_DF_IMAGE_U8 image.
[in]	matrix	The perspective matrix. Must be 3x3 of type VX_TYPE_FLOAT32.
[in]	type	The interpolation type from vx_interpolation_type_e. VX_INTERPOLATION_TYPE_AREA is not supported.
[out]	output	The output VX_DF_IMAGE_U8 image.

Note

Only VX_NODE_ATTRIBUTE_BORDER_MODE value VX_BORDER_MODE_UNDEFINED or VX_BORDER_MODE_CONSTANT is supported.

Returns

vx_node.

Return values

0	Node could not be created.
*	Node handle.

vx_status vxuWarpPerspective	(	vx_context	context,
		vx_image	input,
		vx_matrix	matrix,
		vx_enum	type,
		vx_image	output
	)

[Immediate] Performs an Perspective warp on an image.

Parameters

[in]	context	The reference to the overall context.
[in]	input	The input VX_DF_IMAGE_U8 image.
[in]	matrix	The perspective matrix. Must be 3x3 of type VX_TYPE_FLOAT32.
[in]	type	The interpolation type from vx_interpolation_type_e. VX_INTERPOLATION_TYPE_AREA is not supported.
[out]	output	The output VX_DF_IMAGE_U8 image.

Returns

A vx_status_e enumeration.

Return values

VX_SUCCESS	Success
*	An error occurred. See vx_status_e.