VXLIB_scaleImageNearest_i8u_o8u

Functions
VXLIB_STATUS	VXLIB_scaleImageNearest_i8u_o8u (const uint8_t src[restrict], const VXLIB_bufParams2D_t *src_addr, uint8_t dst[restrict], const VXLIB_bufParams2D_t *dst_addr, VXLIB_F32 xScale, VXLIB_F32 yScale, int16_t srcOffsetX, int16_t srcOffsetY, int16_t dstOffsetX, int16_t dstOffsetY)
VXLIB_STATUS	VXLIB_scaleImageNearest_i8u_o8u_checkParams (const uint8_t src[restrict], const VXLIB_bufParams2D_t *src_addr, uint8_t dst[restrict], const VXLIB_bufParams2D_t *dst_addr, VXLIB_F32 xScale, VXLIB_F32 yScale, int16_t srcOffsetX, int16_t srcOffsetY, int16_t dstOffsetX, int16_t dstOffsetY)

Detailed Description

Function Documentation

VXLIB_scaleImageNearest_i8u_o8u()

VXLIB_STATUS VXLIB_scaleImageNearest_i8u_o8u	(	const uint8_t	src[restrict],
		const VXLIB_bufParams2D_t *	src_addr,
		uint8_t	dst[restrict],
		const VXLIB_bufParams2D_t *	dst_addr,
		VXLIB_F32	xScale,
		VXLIB_F32	yScale,
		int16_t	srcOffsetX,
		int16_t	srcOffsetY,
		int16_t	dstOffsetX,
		int16_t	dstOffsetY
	)

Performs image rescale from input image (8-bit) to output image (8-bit) using nearest neighbor interpolation.

Method:

Parameters

[in]	src[]	Pointer to array containing first input image (UQ8.0)
[in]	src_addr[]	Pointer to structure containing dimensional information of src
[out]	dst[]	Pointer to array containing output image (UQ8.0)
[in]	dst_addr[]	Pointer to structure containing dimensional information of dst
[in]	xScale	Parameter indicating x scale factor from output to input (F32)
[in]	yScale	Parameter indicating y scale factor from output to input (F32)
[in]	srcOffsetX	Parameter indicating x offset of src pointer relative to start of valid data in broader image (SQ15.0)
[in]	srcOffsetY	Parameter indicating y offset of src pointer relative to start of valid data in broader image (SQ15.0)
[in]	dstOffsetX	Parameter indicating x offset of dst pointer relative to start of output valid data in broader image (SQ15.0)
[in]	dstOffsetY	Parameter indicating y offset of dst pointer relative to start of output valid data in broader image (SQ15.0)

Assumptions:

• I/O buffer pointers are assumed to be not aliased.
• If a user wants to divide processing of the image into smaller blocks, then it can use the dstOffsetX and dstOffsetY to indicate the starting coordinate of the output block relative to the start of the full output image, and srcOffsetX and srcOffsetY to indicate the starting coordinate of the input block relative to the start of the full input image.
• xScale and yScale are available on the API instead of computing them internally using the buffer sizes in order to support block-based processing. The expected values are: xScale = (input image width) / (output image width) yScale = (input image height) / (output image height)

• When breaking input image processing into blocks, be sure to fetch enough overlap pixels from the input for interior edges for the rescale, or else the function may put a false border within the block edge of of the output image. For each dimension, the required fetch amount should be:

  • input block width to fetch = ((output block width + 2) * xScale) + 2
  • input block height to fetch = ((output block height + 2) * yScale) + 2

  And the amount of left/top overlap to refetch should be:

  • left edge overlap = ((input block width to fetch) - (input block width)) / 2
  • top edge overlap = ((input block height to fetch) - (input block height)) / 2

Performance Considerations:

• For best performance, the following parameter settings are recommended:
  • Set dst width values to a multiple of 4

VXLIB_scaleImageNearest_i8u_o8u_checkParams()

VXLIB_STATUS VXLIB_scaleImageNearest_i8u_o8u_checkParams	(	const uint8_t	src[restrict],
		const VXLIB_bufParams2D_t *	src_addr,
		uint8_t	dst[restrict],
		const VXLIB_bufParams2D_t *	dst_addr,
		VXLIB_F32	xScale,
		VXLIB_F32	yScale,
		int16_t	srcOffsetX,
		int16_t	srcOffsetY,
		int16_t	dstOffsetX,
		int16_t	dstOffsetY
	)

Description:

Checks the parameters for programming errors for the VXLIB_scaleImageNearest_i8u_o8u function.

Method:

The following checks are made:

• There shall be no NULL pointers
• The strides of each image shall be equal to or greater than the x dimension

Parameters

[in]	src[]	Pointer to array containing first input image (UQ8.0)
[in]	src_addr[]	Pointer to structure containing dimensional information of src
[out]	dst[]	Pointer to array containing output image (UQ8.0)
[in]	dst_addr[]	Pointer to structure containing dimensional information of dst
[in]	xScale	Parameter indicating x scale factor from output to input (F32)
[in]	yScale	Parameter indicating y scale factor from output to input (F32)
[in]	srcOffsetX	Parameter indicating x offset of src pointer relative to start of valid data in broader image (SQ15.0)
[in]	srcOffsetY	Parameter indicating y offset of src pointer relative to start of valid data in broader image (SQ15.0)
[in]	dstOffsetX	Parameter indicating x offset of dst pointer relative to start of output valid data in broader image (SQ15.0)
[in]	dstOffsetY	Parameter indicating y offset of dst pointer relative to start of output valid data in broader image (SQ15.0)