LANCIR image resizer class. More...

#include <lancir.h>

Classes
class	CResizeFilters
	Class for fractional delay filter bank storage and calculation. More...

struct	CResizePos
	Structure defines source scanline positions and filters for each destination pixel. More...

class	CResizeScanline
	Scanline resizing positions class. More...

Public Member Functions
template<typename Tin, typename Tout>
int	resizeImage (const Tin const SrcBuf, const int SrcWidth, const int SrcHeight, const int SrcSSize, Tout const NewBuf, const int NewWidth, const int NewHeight, const int NewSSize, const int ElCount, const double kx0=0.0, const double ky0=0.0, double ox=0.0, double oy=0.0)
	Legacy image resizing function.

template<typename Tin, typename Tout>
int	resizeImage (const Tin const SrcBuf, const int SrcWidth, const int SrcHeight, Tout const NewBuf, const int NewWidth, const int NewHeight, const int ElCount, const CLancIRParams *const aParams=NULL)
	Function resizes an image.

Static Protected Member Functions
template<bool IsOutFloat, bool IsUnityMul, typename T>
static void	outputScanline (const float ip, T op, int l, const int Clamp, const float OutMul)
	Scanline output function.

template<typename Tb, typename Tl>
static void	reallocBuf (Tb *&buf, Tl &len, const Tl newlen)
	Typed buffer reallocation function.

template<typename Tb, typename Tl>
static void	reallocBuf (Tb &buf0, Tb &buf, Tl &len, Tl newlen)
	Typed buffer reallocation function, with address alignment.

static int	roundclamp (const float v, const int Clamp)
	Function rounds a value and applies clamping.


template<typename T>
static void	copyScanline1v (const T ip, const size_t ipinc, float op, int cc, int repl, int repr)
	Scanline copying function, for vertical resizing.

template<typename T>
static void	copyScanline2v (const T ip, const size_t ipinc, float op, int cc, int repl, int repr)

template<typename T>
static void	copyScanline3v (const T ip, const size_t ipinc, float op, int cc, int repl, int repr)

template<typename T>
static void	copyScanline4v (const T ip, const size_t ipinc, float op, int cc, int repl, int repr)


static void	padScanline1h (float *op, CResizeScanline &rs, const int l)
	Scanline padding function, for horizontal resizing.

static void	padScanline2h (float *op, CResizeScanline &rs, const int l)

static void	padScanline3h (float *op, CResizeScanline &rs, const int l)

static void	padScanline4h (float *op, CResizeScanline &rs, const int l)


template<bool UseSP>
static void	resize1 (const float const sp, float op, const size_t opinc, const CResizePos *rp, const int kl, const int DstLen)
	Function performs scanline resizing. Variants for 1-4-channel images.

template<bool UseSP>
static void	resize2 (const float const sp, float op, const size_t opinc, const CResizePos *rp, const int kl, const int DstLen)

template<bool UseSP>
static void	resize3 (const float const sp, float op, const size_t opinc, const CResizePos *rp, const int kl, const int DstLen)

template<bool UseSP>
static void	resize4 (const float const sp, float op, const size_t opinc, const CResizePos *rp, const int kl, const int DstLen)

Protected Attributes
float *	FltBuf
	Address-aligned `FltBuf0`.

float *	FltBuf0
	Intermediate resizing buffer.

size_t	FltBuf0Len
	Length of `FltBuf0`.

CResizeFilters	rfh0
	Resizing filters for horizontal resizing (may not be in use).

CResizeFilters	rfv
	Resizing filters for vertical resizing.

CResizeScanline	rsh
	Horizontal resize scanline.

CResizeScanline	rsv
	Vertical resize scanline.

float *	spv
	Address-aligned `spv0`.

float *	spv0
	Scanline buffer for vertical resizing, also used at the output stage.

int	spv0len
	Length of `spv0`.

Detailed Description

LANCIR image resizer class.

The object of this class can be used to resize 1-4 channel images to any required size. Resizing is performed by utilizing Lanczos filters, with 8-bit precision. This class offers a kind of "optimal" Lanczos resampling implementation.

Object of this class can be allocated on stack.

Note that object of this class does not free temporary buffers and variables after the resizeImage() function call (until object's destruction): these buffers are reused (or reallocated) on subsequent calls, thus making batch resizing of images faster. This means resizing is not thread-safe: a separate CLancIR object should be created for each thread.

Member Function Documentation

◆ copyScanline1v()

template<typename T>

static void avir::CLancIR::copyScanline1v	(	const T *	ip,
		const size_t	ipinc,
		float *	op,
		int	cc,
		int	repl,
		int	repr )

staticprotected

Scanline copying function, for vertical resizing.

Function copies scanline (fully or partially) from the source buffer, in its native format, to the internal scanline buffer, in preparation for vertical resizing. Variants for 1-4-channel images.

Parameters

ip	Source scanline buffer pointer.
ipinc	`ip` increment per pixel.
op	Output scanline pointer.
cc	Source pixel copy count.
repl	Leftmost pixel's replication count.
repr	Rightmost pixel's replication count.

Template Parameters

T	Source buffer's element type.

◆ outputScanline()

template<bool IsOutFloat, bool IsUnityMul, typename T>

static void avir::CLancIR::outputScanline	(	const float *	ip,
		T *	op,
		int	l,
		const int	Clamp,
		const float	OutMul )

staticprotected

Scanline output function.

Function performs output of the scanline pixels to the destination image buffer, with type conversion, scaling, clamping, if necessary.

Parameters

[in]	ip	Input (resized) scanline. Pointer must be aligned to LANCIR_ALIGN bytes.
[out]	op	Output image buffer. Must be different to `ip`.
	l	Output scanline's length, in elements (not pixel count).
	Clamp	Clamp high level, used if `IsOutFloat` is `false`.
	OutMul	Output multiplier, for value range conversion, applied before clamping.

Template Parameters

IsOutFloat	`true` if floating-point output, and no clamping is necessary.
IsUnityMul	`true` if multiplication is optional. However, even if this parameter was specified as `true`, `OutMul` must be 1.
T	Output buffer's element type. Acquired implicitly.

◆ padScanline1h()

static void avir::CLancIR::padScanline1h	(	float *	op,
		CResizeScanline &	rs,
		const int	l )

staticprotected

Scanline padding function, for horizontal resizing.

Function pads the specified scanline buffer to the left and right by replicating its first and last available pixels, in preparation for horizontal resizing. Variants for 1-4-channel images.

Parameters

[in,out]	op	Scanline buffer to pad.
	rs	Scanline resizing positions object.
	l	Source scanline's length, in pixels.

◆ reallocBuf() [1/2]

template<typename Tb, typename Tl>

static void avir::CLancIR::reallocBuf	(	Tb *&	buf,
		Tl &	len,
		const Tl	newlen )

staticprotected

Typed buffer reallocation function.

Function reallocates a typed buffer if its current length is smaller than the required length.

Parameters

buf	Reference to the pointer of the previously allocated buffer; address alignment will not be applied.
len	The current length of the `buf0`.
newlen	A new required length.

Template Parameters

Tb	Buffer element type.
Tl	Length variable type.

◆ reallocBuf() [2/2]

template<typename Tb, typename Tl>

static void avir::CLancIR::reallocBuf	(	Tb *&	buf0,
		Tb *&	buf,
		Tl &	len,
		Tl	newlen )

staticprotected

Typed buffer reallocation function, with address alignment.

Function reallocates a typed buffer if its current length is smaller than the required length, applies LANCIR_ALIGN address alignment to the buffer pointer.

Parameters

buf0	Reference to the pointer of the previously allocated buffer.
buf	Reference to address-aligned `buf0` pointer.
len	The current length of the `buf0`.
newlen	A new required length.

Template Parameters

Tb	Buffer element type.
Tl	Length variable type.

◆ resize1()

template<bool UseSP>

static void avir::CLancIR::resize1	(	const float *const	sp,
		float *	op,
		const size_t	opinc,
		const CResizePos *	rp,
		const int	kl,
		const int	DstLen )

staticprotected

Function performs scanline resizing. Variants for 1-4-channel images.

Parameters

[in]	sp	Source scanline buffer.
[out]	op	Destination buffer.
	opinc	`op` increment.
	rp	Source scanline offsets and resizing filters.
	kl	Filter kernel's length, in taps (always an even value).
	DstLen	Destination length, in pixels.

Template Parameters

UseSP true if sp pointer should be added to spo.

◆ resizeImage() [1/2]

template<typename Tin, typename Tout>

int avir::CLancIR::resizeImage	(	const Tin *const	SrcBuf,
		const int	SrcWidth,
		const int	SrcHeight,
		const int	SrcSSize,
		Tout *const	NewBuf,
		const int	NewWidth,
		const int	NewHeight,
		const int	NewSSize,
		const int	ElCount,
		const double	kx0 = 0.0,
		const double	ky0 = 0.0,
		double	ox = 0.0,
		double	oy = 0.0 )

Legacy image resizing function.

Not recommended for new projects. See the prior resizeImage() function and CLancIRParams class for details.

Parameters

[in]	SrcBuf	Source image buffer.
	SrcWidth	Source image width, in pixels.
	SrcHeight	Source image height, in pixels.
	SrcSSize	Physical size of the source scanline, in elements (not bytes).
[out]	NewBuf	Buffer to accept the resized image. Cannot be equal to SrcBuf.
	NewWidth	New image width, in pixels.
	NewHeight	New image height, in pixels.
	NewSSize	Physical size of the destination scanline, in elements (not bytes).
	ElCount	The number of elements (channels) used to store each source and destination pixel (1-4).
	kx0	Resizing step - horizontal.
	ky0	Resizing step - vertical. Same as `kx0`.
	ox	Start X pixel offset within the source image.
	oy	Start Y pixel offset within the source image.

Template Parameters

Tin	Input buffer's element type.
Tout	Output buffer's element type.

Returns: The number of available output scanlines. Equals to NewHeight, or 0 on function parameters error.

◆ resizeImage() [2/2]

template<typename Tin, typename Tout>

int avir::CLancIR::resizeImage	(	const Tin *const	SrcBuf,
		const int	SrcWidth,
		const int	SrcHeight,
		Tout *const	NewBuf,
		const int	NewWidth,
		const int	NewHeight,
		const int	ElCount,
		const CLancIRParams *const	aParams = NULL )

Function resizes an image.

Performs input-to-output type conversion, if necessary.

Parameters

[in]	SrcBuf	Source image buffer.
	SrcWidth	Source image width, in pixels.
	SrcHeight	Source image height, in pixels.
[out]	NewBuf	Buffer to accept the resized image. Cannot be equal to SrcBuf.
	NewWidth	New image width, in pixels.
	NewHeight	New image height, in pixels.
	ElCount	The number of elements (channels) used to store each source and destination pixel (1-4).

Template Parameters

Tin	Input buffer's element type. Can be uint8_t (0-255 value range), uint16_t (0-65535 value range), float (0-1 value range), double (0-1 value range). uint32_t type is treated as uint16_t. Signed integer types and larger integer types are unsupported.
Tout	Output buffer's element type, treated like `Tin`. If `Tin` and `Tout` types do not match, an output value scaling will be applied. Floating-point output will not be clamped/clipped/saturated, integer output is always rounded and clamped.

Returns: The number of available output scanlines. Equals to NewHeight, or 0 on function parameters error.

◆ roundclamp()

static int avir::CLancIR::roundclamp	(	const float	v,
		const int	Clamp )

staticprotected

Function rounds a value and applies clamping.

Parameters

v	Value to round and clamp.
Clamp	High clamp level; low level is 0.

Returns: Rounded and clamped value.

Classes

Public Member Functions

Static Protected Member Functions

Protected Attributes

Detailed Description

Member Function Documentation

◆ copyScanline1v()

◆ outputScanline()

◆ padScanline1h()

◆ reallocBuf() [1/2]

◆ reallocBuf() [2/2]

◆ resize1()

◆ resizeImage() [1/2]

◆ resizeImage() [2/2]

◆ roundclamp()