Flip Image

Detailed Description

The Flip Image Primitive.

This primitive flips the input image in one of three different ways:

\[ dst(y, x) = \left\{ \begin{array}{l l} src(height - y - 1, x) & if\; flip\_mode = NVX\_FLIP\_VERTICAL \\ src(y, width - x - 1) & if\; flip\_mode = NVX\_FLIP\_HORIZONTAL \\ src(height - y - 1, width - x - 1) & if\; flip\_mode = NVX\_FLIP\_BOTH \\ \end{array} \right. \]

The primitive uses the following identifiers:

• NVX_KERNEL_FLIP_IMAGE for vxGetKernelByEnum function;
• "com.nvidia.nvx.flip_image" for vxGetKernelByName function.

Use Cases

The example scenarios of using the function are the following:

• Vertical flipping of the image (flip_mode = NVX_FLIP_VERTICAL) to switch between top-left and bottom-left image origin. This is a typical operation in video processing.
• Horizontal flipping of the image with the subsequent horizontal shift and absolute difference calculation to check for a vertical-axis symmetry (flip_mode = NVX_FLIP_HORIZONTAL).
• Simultaneous horizontal and vertical flipping of the image with the subsequent shift and absolute difference calculation to check for a central symmetry (flip_mode = NVX_FLIP_BOTH).

Example Code

vx_context context = vxCreateContext();
vx_image src = vxCreateImage(context, 640, 480, VX_DF_IMAGE_U8);
vx_image dst = vxCreateImage(context, 640, 480, VX_DF_IMAGE_U8);
vx_enum flip_mode = NVX_FLIP_BOTH;

nvxuFlipImage(context, src, dst, flip_mode);

vxReleaseImage(&src);
vxReleaseImage(&dst);
vxReleaseContext(&context);

Enumerations
enum	nvx_flip_mode_e {   NVX_FLIP_HORIZONTAL,   NVX_FLIP_VERTICAL,   NVX_FLIP_BOTH }
	Defines modes for flip image operation. More...

Functions
vx_node	nvxFlipImageNode (vx_graph graph, vx_image input, vx_image output, vx_enum flip_mode)
	[Graph] Flips the input image. More...
vx_status	nvxuFlipImage (vx_context context, vx_image input, vx_image output, vx_enum flip_mode)
	[Immediate] Flips the input image. More...

Enumeration Type Documentation

enum nvx_flip_mode_e

Defines modes for flip image operation.

Enumerator
NVX_FLIP_HORIZONTAL	Horizontal flipping of the image.
NVX_FLIP_VERTICAL	Vertical flipping of the image.
NVX_FLIP_BOTH	Simultaneous horizontal and vertical flipping of the image.

Definition at line 1039 of file nvx.h.

Function Documentation

vx_node nvxFlipImageNode	(	vx_graph	graph,
		vx_image	input,
		vx_image	output,
		vx_enum	flip_mode
	)

[Graph] Flips the input image.

Parameters

[in]	graph	Specifies the graph.
[in]	input	Specifies the input image. Supported formats: VX_DF_IMAGE_U8, VX_DF_IMAGE_RGB, VX_DF_IMAGE_RGBX.
[out]	output	Specifies the output image. It should have the same size and format as the input image. Output size and format can be automatically determined for virtual images.
[in]	flip_mode	The flipping mode (see nvx_flip_mode_e).

Returns

A valid node reference or an error object (use vxGetStatus).

vx_status nvxuFlipImage	(	vx_context	context,
		vx_image	input,
		vx_image	output,
		vx_enum	flip_mode
	)

[Immediate] Flips the input image.

Parameters

[in]	context	Specifies the context.
[in]	input	Specifies the input image. Supported formats: VX_DF_IMAGE_U8, VX_DF_IMAGE_RGB, VX_DF_IMAGE_RGBX.
[out]	output	Specifies the output image. It should have the same size and format as the input image.
[in]	flip_mode	The flipping mode (see nvx_flip_mode_e).

Returns

A vx_status enumerator.

Return values

VX_SUCCESS	No errors.
VX_ERROR_INVALID_REFERENCE	Supplied parameters are not a valid references.
VX_ERROR_INVALID_PARAMETERS	Supplied parameters are not valid.
VX_ERROR_INVALID_SCOPE	Supplied parameters are virtual objects, which can't be used in immediate mode.
VX_FAILURE	Internal error in primitive implementation, check log for detailed information (Framework: Log).