interpolation.c File Reference

#include "common/interpolation.h"
#include "common/darktable.h"
#include "common/math.h"
#include "control/conf.h"
#include <assert.h>
#include <glib.h>
#include <inttypes.h>
#include <stddef.h>
#include <stdint.h>

Include dependency graph for interpolation.c:

Macros
#define	RESAMPLING_BORDER_MODE   BORDER_REPLICATE
#define	INTERPOLATION_BORDER_MODE   BORDER_MIRROR
#define	MAX_HALF_FILTER_WIDTH   3
#define	DEBUG_PRINT_VERBOSE   0
#define	DT_LANCZOS_EPSILON   (1e-9f)
#define	MAX_KERNEL_REQ   ((2 * (MAX_HALF_FILTER_WIDTH) + 3) & (~3))

Enumerations
enum	border_mode {   BORDER_REPLICATE ,   BORDER_WRAP ,   BORDER_MIRROR ,   BORDER_CLAMP }

Functions
static ssize_t	_clip (ssize_t i, const ssize_t min, const ssize_t max, enum border_mode mode)
static void	_prepare_tap_boundaries (int *tap_first, int *tap_last, const enum border_mode mode, const int filterwidth, const int t, const int max)
static float	_maketaps_bilinear (float *taps, const size_t num_taps, const float width, const float first_tap, const float interval)
static float	_maketaps_bicubic (float *taps, const size_t num_taps, const float width, const float first_tap, const float interval)
static float	_maketaps_lanczos (float *taps, const size_t num_taps, const float width, const float first_tap, const float interval)
static float	_compute_upsampling_kernel (const struct dt_interpolation *itor, float *kernel, int *first, float t)
static void	_compute_downsampling_kernel (const struct dt_interpolation *itor, int *taps, int *first, float *kernel, float *norm, const float outoinratio, const int xout)
float	dt_interpolation_compute_sample (const struct dt_interpolation *itor, const float *in, const float x, const float y, const int width, const int height, const int samplestride, const int linestride)
void	dt_interpolation_compute_pixel4c (const struct dt_interpolation *itor, const float *in, float *out, const float x, const float y, const int width, const int height, const int linestride)
const struct dt_interpolation *	dt_interpolation_new (enum dt_interpolation_type type)
static gboolean	_prepare_resampling_plan (const struct dt_interpolation *itor, const int in, const int in_x0, const int out, const int out_x0, const float scale, int **plength, float **pkernel, int **pindex, int **pmeta)
static void	_interpolation_resample_plain (const struct dt_interpolation *itor, float *out, const dt_iop_roi_t *const roi_out, const float *const in, const dt_iop_roi_t *const roi_in)
void	dt_interpolation_resample (const struct dt_interpolation *itor, float *out, const dt_iop_roi_t *const roi_out, const float *const in, const dt_iop_roi_t *const roi_in)
void	dt_interpolation_resample_roi (const struct dt_interpolation *itor, float *out, const dt_iop_roi_t *const roi_out, const float *const in, const dt_iop_roi_t *const roi_in)
static void	_interpolation_resample_1c_plain (const struct dt_interpolation *itor, float *out, const dt_iop_roi_t *const roi_out, const float *const in, const dt_iop_roi_t *const roi_in)
void	dt_interpolation_resample_1c (const struct dt_interpolation *itor, float *out, const dt_iop_roi_t *const roi_out, const float *const in, const dt_iop_roi_t *const roi_in)
void	dt_interpolation_resample_roi_1c (const struct dt_interpolation *itor, float *out, const dt_iop_roi_t *const roi_out, const float *const in, const dt_iop_roi_t *const roi_in)

Variables
static const struct dt_interpolation	dt_interpolator []

Macro Definition Documentation

DEBUG_PRINT_VERBOSE

#define DEBUG_PRINT_VERBOSE   0

DT_LANCZOS_EPSILON

#define DT_LANCZOS_EPSILON   (1e-9f)

INTERPOLATION_BORDER_MODE

#define INTERPOLATION_BORDER_MODE   BORDER_MIRROR

MAX_HALF_FILTER_WIDTH

#define MAX_HALF_FILTER_WIDTH   3

MAX_KERNEL_REQ

#define MAX_KERNEL_REQ   ((2 * (MAX_HALF_FILTER_WIDTH) + 3) & (~3))

RESAMPLING_BORDER_MODE

#define RESAMPLING_BORDER_MODE   BORDER_REPLICATE

Enumeration Type Documentation

border_mode

enum border_mode

Border extrapolation modes

Enumerator
BORDER_REPLICATE
BORDER_WRAP
BORDER_MIRROR
BORDER_CLAMP

Function Documentation

_clip()

static ssize_t _clip ( ssize_t  i, const ssize_t  min, const ssize_t  max, enum border_mode  mode  )

inlinestatic

Clip into specified range

Parameters

idx	index to filter
length	length of line

References BORDER_CLAMP, BORDER_MIRROR, BORDER_REPLICATE, and BORDER_WRAP.

Referenced by _prepare_resampling_plan(), dt_interpolation_compute_pixel4c(), and dt_interpolation_compute_sample().

_compute_downsampling_kernel()

static void _compute_downsampling_kernel ( const struct dt_interpolation *  itor, int *  taps, int *  first, float *  kernel, float *  norm, const float  outoinratio, const int  xout  )

inlinestatic

Computes a downsampling filtering kernel (vectorized version, four taps per inner loop iteration)

Parameters

itor	[in] Interpolator used
kernelsize	[out] Number of taps
kernel	[out] resulting taps (at least itor->width/inoout + 4 elements for no overflow)
norm	[out] Kernel norm
first	[out] index of the first sample for which the kernel is to be applied
outoinratio	[in] "out samples" over "in samples" ratio
xout	[in] Output coordinate

References ceil_fast(), kernel(), dt_interpolation::maketaps, and dt_interpolation::width.

Referenced by _prepare_resampling_plan().

_compute_upsampling_kernel()

static float _compute_upsampling_kernel ( const struct dt_interpolation *  itor, float *  kernel, int *  first, float  t  )

inlinestatic

References f(), kernel(), dt_interpolation::maketaps, and dt_interpolation::width.

Referenced by _prepare_resampling_plan(), dt_interpolation_compute_pixel4c(), and dt_interpolation_compute_sample().

_interpolation_resample_1c_plain()

static void _interpolation_resample_1c_plain ( const struct dt_interpolation *  itor, float *  out, const dt_iop_roi_t *const  roi_out, const float *const  in, const dt_iop_roi_t *const  roi_in  )

static

References _prepare_resampling_plan(), dt_free_align, dt_iop_roi_t::height, dt_iop_roi_t::scale, dt_iop_roi_t::width, dt_iop_roi_t::x, and dt_iop_roi_t::y.

Referenced by dt_interpolation_resample_1c().

_interpolation_resample_plain()

static void _interpolation_resample_plain ( const struct dt_interpolation *  itor, float *  out, const dt_iop_roi_t *const  roi_out, const float *const  in, const dt_iop_roi_t *const  roi_in  )

static

References _prepare_resampling_plan(), copy_pixel(), copy_pixel_nontemporal(), dt_free_align, dt_omploop_sfence, for_each_channel, height, dt_iop_roi_t::height, MAX, dt_iop_roi_t::scale, width, dt_iop_roi_t::width, dt_iop_roi_t::x, and dt_iop_roi_t::y.

Referenced by dt_interpolation_resample().

_maketaps_bicubic()

static float _maketaps_bicubic ( float *  taps, const size_t  num_taps, const float  width, const float  first_tap, const float  interval  )

static

References for_four_channels.

_maketaps_bilinear()

static float _maketaps_bilinear ( float *  taps, const size_t  num_taps, const float  width, const float  first_tap, const float  interval  )

static

References for_four_channels.

_maketaps_lanczos()

static float _maketaps_lanczos ( float *  taps, const size_t  num_taps, const float  width, const float  first_tap, const float  interval  )

static

References DT_LANCZOS_EPSILON, dt_vector_sin(), eps, for_four_channels, M_PI_F, sign(), and width.

_prepare_resampling_plan()

static gboolean _prepare_resampling_plan ( const struct dt_interpolation *  itor, const int  in, const int  in_x0, const int  out, const int  out_x0, const float  scale, int **  plength, float **  pkernel, int **  pindex, int **  pmeta  )

static

Prepares a 1D resampling plan

This consists of the following information

• A list of lengths that tell how many pixels are relevant for the next output
• A list of required filter kernels
• A list of sample indexes

How to apply the resampling plan:

1. Pick a length from the length array
2. until length is reached
   1. pick a kernel tap>
   2. pick the relevant sample according to the picked index
   3. multiply them and accumulate
3. here goes a single output sample

This until you reach the number of output pixels

Parameters

itor	interpolator used to resample
in	[in] Number of input samples
out	[in] Number of output samples
plength	[out] Array of lengths for each pixel filtering (number of taps/indexes to use). This array mus be freed with dt_free_align() when you're done with the plan.
pkernel	[out] Array of filter kernel taps
pindex	[out] Array of sample indexes to be used for applying each kernel tap arrays of information
pmeta	[out] Array of int triplets (length, kernel, index) telling where to start for an arbitrary out position meta[3*out]

Returns

FALSE for success, TRUE for failure

References _clip(), _compute_downsampling_kernel(), _compute_upsampling_kernel(), _prepare_tap_boundaries(), ceil_fast(), dt_alloc_align, DT_CACHELINE_BYTES, dt_round_size(), FALSE, kernel(), meta, RESAMPLING_BORDER_MODE, TRUE, void(), and dt_interpolation::width.

Referenced by _interpolation_resample_1c_plain(), and _interpolation_resample_plain().

_prepare_tap_boundaries()

static void _prepare_tap_boundaries ( int *  tap_first, int *  tap_last, const enum border_mode  mode, const int  filterwidth, const int  t, const int  max  )

inlinestatic

References BORDER_CLAMP.

Referenced by _prepare_resampling_plan(), dt_interpolation_compute_pixel4c(), and dt_interpolation_compute_sample().

dt_interpolation_compute_pixel4c()

void dt_interpolation_compute_pixel4c	(	const struct dt_interpolation *	itor,
		const float *	in,
		float *	out,
		const float	x,
		const float	y,
		const int	width,
		const int	height,
		const int	linestride
	)

Compute an interpolated 4 component pixel.

This function computes a full 4 component pixel. This helps a bit speedwise as interpolation coordinates are supposed to be the same for all components. Thus we can share horizontal and vertical interpolation kernels across all components

NB: a pixel is to be four floats big in stride

Parameters

in	Pointer to the input image
out	Pointer to the output sample
itor	interpolator to be used
x	X-Coordinate of the requested sample
y	Y-Coordinate of the requested sample
width	Width of the input image
height	Width of the input image
linestride	Stride in number of pixels for complete line

References _clip(), _compute_upsampling_kernel(), _prepare_tap_boundaries(), BORDER_CLAMP, copy_pixel(), DT_ALIGNED_ARRAY, for_each_channel, height, INTERPOLATION_BORDER_MODE, MAX_HALF_FILTER_WIDTH, MAX_KERNEL_REQ, width, and dt_interpolation::width.

Referenced by apply_global_distortion_map(), distort_mask(), process(), and process().

dt_interpolation_compute_sample()

float dt_interpolation_compute_sample	(	const struct dt_interpolation *	itor,
		const float *	in,
		const float	x,
		const float	y,
		const int	width,
		const int	height,
		const int	samplestride,
		const int	linestride
	)

Compute a single interpolated sample.

This function computes a single interpolated sample. Implied costs are:

• Horizontal filtering kernel computation
• Vertical filtering kernel computation
• Sample computation

Parameters

in	Input image
itor	interpolator to be used
x	X-Coordinate of the requested sample
y	Y-Coordinate of the requested sample
width	Width of the input image
height	Width of the input image
samplestride	Stride in bytes for a sample
linestride	Stride in bytes for complete line

Returns

computed sample

References _clip(), _compute_upsampling_kernel(), _prepare_tap_boundaries(), BORDER_CLAMP, DT_ALIGNED_ARRAY, height, INTERPOLATION_BORDER_MODE, MAX_HALF_FILTER_WIDTH, MAX_KERNEL_REQ, width, and dt_interpolation::width.

Referenced by apply_global_distortion_map(), distort_mask(), and process().

dt_interpolation_new()

const struct dt_interpolation * dt_interpolation_new

(

enum dt_interpolation_type

type

)

Get an interpolator from type

Parameters

type	Interpolator to search for

Returns

requested interpolator or default if not found (this function can't fail)

References dt_conf_get_string_const(), DT_INTERPOLATION_DEFAULT, DT_INTERPOLATION_DEFAULT_WARP, DT_INTERPOLATION_FIRST, DT_INTERPOLATION_LAST, DT_INTERPOLATION_USERPREF, DT_INTERPOLATION_USERPREF_WARP, dt_interpolator, name, and type.

Referenced by _aspect_ratio_get(), _ratio_get_aspect(), apply_global_distortion_map(), distort_mask(), dt_iop_clip_and_zoom(), dt_iop_clip_and_zoom_roi(), modify_roi_in(), modify_roi_in(), modify_roi_out(), process(), and process().

dt_interpolation_resample()

void dt_interpolation_resample	(	const struct dt_interpolation *	itor,
		float *	out,
		const dt_iop_roi_t *const	roi_out,
		const float *const	in,
		const dt_iop_roi_t *const	roi_in
	)

Applies resampling (re-scaling) on full input and output buffers. roi_in and roi_out define the part of the buffers that is affected.

References _interpolation_resample_plain().

Referenced by dt_interpolation_resample_roi(), and dt_iop_clip_and_zoom().

dt_interpolation_resample_1c()

void dt_interpolation_resample_1c	(	const struct dt_interpolation *	itor,
		float *	out,
		const dt_iop_roi_t *const	roi_out,
		const float *const	in,
		const dt_iop_roi_t *const	roi_in
	)

Applies resampling (re-scaling) on full input and output buffers. roi_in and roi_out define the part of the buffers that is affected.

References _interpolation_resample_1c_plain().

Referenced by dt_interpolation_resample_roi_1c().

dt_interpolation_resample_roi()

void dt_interpolation_resample_roi	(	const struct dt_interpolation *	itor,
		float *	out,
		const dt_iop_roi_t *const	roi_out,
		const float *const	in,
		const dt_iop_roi_t *const	roi_in
	)

Applies resampling (re-scaling) on a specific region-of-interest of an image. The input and output buffers hold exactly those roi's. roi_in and roi_out define the relative positions of the roi's within the full input and output image, respectively.

References dt_interpolation_resample(), dt_iop_roi_t::x, and dt_iop_roi_t::y.

Referenced by dt_iop_clip_and_zoom_roi().

dt_interpolation_resample_roi_1c()

void dt_interpolation_resample_roi_1c	(	const struct dt_interpolation *	itor,
		float *	out,
		const dt_iop_roi_t *const	roi_out,
		const float *const	in,
		const dt_iop_roi_t *const	roi_in
	)

Applies resampling (re-scaling) on a specific region-of-interest of an image. The input and output buffers hold exactly those roi's. roi_in and roi_out define the relative positions of the roi's within the full input and output image, respectively.

References dt_interpolation_resample_1c(), dt_iop_roi_t::x, and dt_iop_roi_t::y.

Referenced by distort_mask().

Variable Documentation

dt_interpolator

const struct dt_interpolation dt_interpolator[]

static

Initial value:

= {
  {.id = DT_INTERPOLATION_BILINEAR,
   .name = "bilinear",
   .width = 1,
   .maketaps = &_maketaps_bilinear,
  },
  {.id = DT_INTERPOLATION_BICUBIC,
   .name = "bicubic",
   .width = 2,
   .maketaps = &_maketaps_bicubic,
  },
  {.id = DT_INTERPOLATION_LANCZOS2,
   .name = "lanczos2",
   .width = 2,
   .maketaps = &_maketaps_lanczos,
  },
  {.id = DT_INTERPOLATION_LANCZOS3,
   .name = "lanczos3",
   .width = 3,
   .maketaps = &_maketaps_lanczos,
  },
}

Referenced by dt_interpolation_new().