Convert Image Format

Converts the image contents to the desired format, with optional pixel value scaling and offset. More...

Data Structures
struct	VPIConvertImageFormatParams
	Parameters for customizing image format conversion. More...

Enumerations
enum	VPIConversionPolicy
	Policy used when converting between image types. More...

Functions
VPIStatus	vpiInitConvertImageFormatParams (VPIConvertImageFormatParams *params)
	Initialize VPIConvertImageFormatParams with default values. More...
VPIStatus	vpiSubmitConvertImageFormat (VPIStream stream, uint32_t backend, VPIImage input, VPIImage output, const VPIConvertImageFormatParams *params)
	Converts the image contents to the desired format, with optional scaling and offset. More...

Detailed Description

Converts the image contents to the desired format, with optional pixel value scaling and offset.

---

Data Structure Documentation

VPIConvertImageFormatParams

struct VPIConvertImageFormatParams

Parameters for customizing image format conversion.

These parameters are used to customize how the conversion will be made. Make sure to call vpiInitConvertImageFormatParams to initialize this structure before updating its attributes. This guarantees that new attributes added in future versions will have a suitable default value assigned.

Definition at line 84 of file ConvertImageFormat.h.

Collaboration diagram for VPIConvertImageFormatParams:

Data Fields
VPIInterpolationType	chromaDownFilter	Interpolation to use for chroma downsampling. Note Currently all backends support VPI_INTERP_NEAREST only. Different values will be silently ignored.
VPIInterpolationType	chromaUpFilter	Interpolation to use for chroma upsampling. Note VIC backend on Jetson Nano devices doesn't allow choosing of chroma upsampling filter. It will only use VPI_INTERP_NEAREST, no matter what value is chosen here.
uint32_t	flags
float	offset	Offset factor. Pass 0 for no offset. Control flags. Valid values: 0: default, negation of all other flags. VPI_PRECISE : precise, potentially slower implementation.
VPIConversionPolicy	policy	Conversion policy to be used.
float	scale	Scaling factor. Pass 1 for no scaling.

Enumeration Type Documentation

VPIConversionPolicy

enum VPIConversionPolicy

#include <vpi/Types.h>

Policy used when converting between image types.

Enumerator
VPI_CONVERSION_CLAMP	Clamps input to output's type range. Overflows and underflows are mapped to the output type's maximum and minimum representable value, respectively. When output type is floating point, clamp behaves like cast.
VPI_CONVERSION_CAST	Casts input to the output type. Overflows and underflows are handled as per C specification, including situations of undefined behavior.
VPI_CONVERSION_INVALID	Invalid conversion.

Definition at line 248 of file Types.h.

Function Documentation

vpiInitConvertImageFormatParams()

VPIStatus vpiInitConvertImageFormatParams

(

VPIConvertImageFormatParams *

params

)

#include <vpi/algo/ConvertImageFormat.h>

Initialize VPIConvertImageFormatParams with default values.

The following parameters are set:

• policy: VPI_CONVERSION_CLAMP
• scale: 1
• offset: 0
• flags: 0
• chromaUpFilter: VPI_INTERP_LINEAR
• chromaDownFilter: VPI_INTERP_LINEAR

Parameters

[out]

params

Pointer to structure to be filled. Must not be NULL.

Returns

An error code if params is NULL, VPI_SUCCESS otherwise.

vpiSubmitConvertImageFormat()

VPIStatus vpiSubmitConvertImageFormat	(	VPIStream	stream,
		uint32_t	backend,
		VPIImage	input,
		VPIImage	output,
		const VPIConvertImageFormatParams *	params
	)

#include <vpi/algo/ConvertImageFormat.h>

Converts the image contents to the desired format, with optional scaling and offset.

The input and output types are inferred from the corresponding images passed as parameters. When scaling and offset are fractional, input is converted to 32-bit floating point prior conversion takes place. The formula that relates input and output pixels is:

\[ out(x,y) = clamp_{[\mathsf{min_{out}},\mathsf{max_{out}}]}(in(x,y)*\alpha + \beta) \]

where:

• \(\mathsf{min_{out}}\) and \(\mathsf{max_{out}}\) are the minimum and maximum representable value by output image format. Exception is for floating point types, where limits are \([-\infty,\infty]\), i.e., no clamping is done.
• \(\alpha\) is the scaling.
• \(\beta\) is the offset.

float to integer conversion does returns the nearest integer number, rounding halfway cases away from zero.

When passing NULL as params argument, it'll use default values as the ones set by vpiInitConvertImageFormatParams.

Parameters

[in]	stream	A stream handle where the operation will be queued into.
[in]	backend	Backend that will execute the algorithm.
[in]	input	Input image to be converted.
[out]	output	Output image where result will be written to, with the desired type.
[in]	params	Optional parameters. Pass NULL for default.

Returns

an error code on failure else VPI_SUCCESS