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|
%% options
copyright owner = Dirk Krause
copyright year = 2017-xxxx
SPDX-License-Identifier: BSD-3-Clause
%% header
/** @file dk4pxres.h Pixel resampling.
*/
#ifndef DK4CONF_H_INCLUDED
#if DK4_BUILDING_DKTOOLS4
#include "dk4conf.h"
#else
#include <dktools-4/dk4conf.h>
#endif
#endif
#ifndef DK4PXBIT_H_INCLUDED
#if DK4_BUILDING_DKTOOLS4
#include "dk4pxbit.h"
#else
#include <dktools-4/dk4pxbit.h>
#endif
#endif
/** Structure to resample pixels.
*/
typedef struct {
unsigned long nom; /**< Nominator in scale factor. */
unsigned long denom; /**< Denominator in scale factor. */
unsigned long denom2; /**< Half of the denominator. */
} dk4_px_resample_t;
#ifdef __cplusplus
extern "C" {
#endif
/** Initialize resampler structure.
@param pxrptr Resampler structure to initialize.
*/
void
dk4pxres_init(dk4_px_resample_t *pxrptr);
/** Set up resample structure for conversions.
@param pxrptr Resample structure to set up.
@param ibits Number of input bits.
@param obits Number of output (result) bits.
@return 1 on success, 0 on error.
*/
int
dk4pxres_setup(
dk4_px_resample_t *pxrptr,
size_t ibits,
size_t obits
);
/** Set up resample structure for conversions for unusual maxval values.
Input is from a range with unusual maxval, output is prepared
for a given bit depth.
@param pxrptr Resample structure to set up.
@param imaxval Maximum value for input pixel data.
@param obits Number of output (result) bits.
@return 1 on success, 0 on error.
*/
int
dk4pxres_setup_from_maxval(
dk4_px_resample_t *pxrptr,
dk4_px_t imaxval,
size_t obits
);
/** Set up resample structure for conversions for unusual maxval values.
Input has a given bit depth, output must be in the range up to s
specified maxval.
@param pxrptr Resample structure to set up.
@param ibits Input bit depth.
@param omaxval Maximum value for output pixel data.
@return 1 on success, 0 on error.
*/
int
dk4pxres_setup_to_maxval(
dk4_px_resample_t *pxrptr,
size_t ibits,
dk4_px_t omaxval
);
/** Resample pixel component from old bit width to new bit width.
@param pxrptr Resample structure to use.
@param in Component value in old bit depth.
@return Resampling result (component value in new bit depth).
*/
dk4_px_t
dk4pxres_get(
dk4_px_resample_t const *pxrptr,
dk4_px_t in
);
/** Check whether a component value can be resampled without quality loss.
@param pxrptr Resample structure to use.
@param in Component value in old bit depth.
@return 1 on success (no division remainder), 0 on error
(skipped division remainder results in quality loss).
*/
int
dk4pxres_check(
dk4_px_resample_t const *pxrptr,
dk4_px_t in
);
/** Resample multiple values to new bit depth.
@param dptr Array containing values to resample, results on output.
@param dsz Number of elements in array.
@param pxrptr Resample structure to use.
@return 1 on success, 0 on error.
*/
int
dk4pxres_multiple(
dk4_px_t *dptr,
size_t dsz,
dk4_px_resample_t const *pxrptr
);
#ifdef __cplusplus
}
#endif
/* vim: set ai sw=4 ts=4 : */
%% module
#include "dk4conf.h"
#ifndef DK4PXRES_H_INCLUDED
#include "dk4pxres.h"
#endif
#ifndef DK4PXBIT_H_INCLUDED
#include "dk4pxbit.h"
#endif
#if DK4_HAVE_ASSERT_H
#ifndef ASSERT_H_INCLUDED
#include <assert.h>
#define ASSERT_H_INCLUDED 1
#endif
#endif
$!trace-include
void
dk4pxres_init(dk4_px_resample_t *pxrptr)
{
$? "+ dk4pxres_init ptr=%d", TR_IPTR(pxrptr)
#if DK4_USE_ASSERT
assert(NULL != pxrptr);
#endif
if (NULL != pxrptr) {
pxrptr->nom = 255UL;
pxrptr->denom = 255UL;
pxrptr->denom2 = 127UL;
}
$? "- dk4pxres_init"
}
int
dk4pxres_setup(
dk4_px_resample_t *pxrptr,
size_t ibits,
size_t obits
)
{
dk4_px_t nom;
dk4_px_t denom;
int back = 0;
$? "+ dk4pxres_setup in=%u out=%u", (unsigned)ibits, (unsigned)obits
#if DK4_USE_ASSERT
assert(NULL != pxrptr);
#endif
/*
Check pointer
*/
if (NULL == pxrptr) {
goto finished;
}
pxrptr->nom = 255UL;
pxrptr->denom = 255UL;
pxrptr->denom2 = 127UL;
/*
Attempt to retrieve values
*/
nom = dk4pxbit_get_max(obits);
denom = dk4pxbit_get_max(ibits);
if ((0 == nom) || (0 == denom)) {
goto finished;
}
/*
Set values and indicate success
*/
pxrptr->nom = (unsigned long)nom;
pxrptr->denom = (unsigned long)denom;
pxrptr->denom2 = pxrptr->denom / 2UL;
$? ". factor = %lu / %lu", (unsigned long)nom, (unsigned long)denom
back = 1;
finished:
$? "- dk4pxres_setup %d", back
return back;
}
int
dk4pxres_setup_from_maxval(
dk4_px_resample_t *pxrptr,
dk4_px_t imaxval,
size_t obits
)
{
int back = 0;
unsigned long nom;
unsigned long denom;
$? "+ dk4pxres_setup_from_maxval p=%d maxval=%u obits=%u", TR_IPTR(pxrptr), (unsigned)imaxval, (unsigned)obits
#if DK4_USE_ASSERT
assert(NULL != pxrptr);
#endif
/*
Check pointer
*/
if (NULL == pxrptr) {
goto finished;
}
/*
Set defaults
*/
pxrptr->nom = 255UL;
pxrptr->denom = 255UL;
pxrptr->denom2 = 127UL;
/*
Retrieve values
*/
nom = dk4pxbit_get_max(obits);
if ((0 == nom) || (0 == imaxval)) {
goto finished;
}
/* Set values and indicate success
*/
pxrptr->nom = (unsigned long)nom;
pxrptr->denom = denom = (unsigned long)imaxval;
pxrptr->denom2 = (unsigned long)imaxval / 2UL;
$? ". factor = %lu / %lu", (unsigned long)nom, (unsigned long)denom
back = 1;
finished:
$? "- dk4pxres_setup_from_maxval %d", back
return back;
}
int
dk4pxres_setup_to_maxval(
dk4_px_resample_t *pxrptr,
size_t ibits,
dk4_px_t omaxval
)
{
unsigned long nom;
unsigned long denom;
int back = 0;
$? "+ dk4pxres_setup_to_maxval"
#if DK4_USE_ASSERT
assert(NULL != pxrptr);
#endif
/*
Check pointer
*/
if (NULL == pxrptr) { goto finished; }
/*
Set defaults
*/
pxrptr->nom = 255UL;
pxrptr->denom = 255UL;
pxrptr->denom2 = 127UL;
/*
Find nominator and denominator
*/
nom = (unsigned long)omaxval;
denom = (unsigned long)dk4pxbit_get_max(ibits);
if ((0UL == nom) || (0UL == denom)) { goto finished; }
pxrptr->nom = nom;
pxrptr->denom = denom;
pxrptr->denom2 = denom / 2UL;
$? ". factor = %lu / %lu", nom, denom
back = 1;
finished:
$? "- dk4pxres_setup_to_maxval %d", back
return back;
}
dk4_px_t
dk4pxres_get(
dk4_px_resample_t const *pxrptr,
dk4_px_t in
)
{
unsigned long prod;
dk4_px_t back = 0U;
$? "+ dk4pxres_get %lu", (unsigned long)in
#if DK4_USE_ASSERT
assert(NULL != pxrptr);
#endif
/*
Check pointer
*/
if (NULL == pxrptr) {
goto finished;
}
/*
Leave value unchanged for equal size
*/
if (pxrptr->nom == pxrptr->denom) {
back = in;
goto finished;
}
/*
Calculate
*/
if (0 == pxrptr->denom) {
goto finished;
}
prod = (unsigned long)in * pxrptr->nom;
back = (dk4_px_t)(prod / pxrptr->denom);
if (pxrptr->denom2 < (prod % pxrptr->denom)) {
back++;
}
finished:
$? "- dk4pxres_get %lu", (unsigned long)back
return back;
}
int
dk4pxres_check(
dk4_px_resample_t const *pxrptr,
dk4_px_t in
)
{
unsigned long prod;
int back = 0;
$? "+ dk4pxres_check %lu", (unsigned long)in
#if DK4_USE_ASSERT
assert(NULL != pxrptr);
#endif
if (NULL == pxrptr) {
goto finished;
}
if (pxrptr->nom == pxrptr->denom) {
back = 1;
goto finished;
}
if (0 == pxrptr->denom) {
goto finished;
}
prod = (unsigned long)in * pxrptr->nom;
if (0 == (prod % pxrptr->denom)) {
back = 1;
}
finished:
$? "- dk4pxres_check %d", back
return back;
}
int
dk4pxres_multiple(
dk4_px_t *dptr,
size_t dsz,
dk4_px_resample_t const *pxrptr
)
{
int back = 0;
$? "+ dk4pxres_multiple %u", (unsigned)dsz
#if DK4_USE_ASSERT
assert(NULL != dptr);
assert(0 < dsz);
#endif
if ((NULL == dptr) || (NULL == pxrptr)) {
goto finished;
}
back = 1;
while (0 < dsz--) {
*dptr = dk4pxres_get(pxrptr, *dptr);
dptr++;
}
finished:
$? "- dk4pxres_multiple %d", back
return back;
}
/* vim: set ai sw=4 ts=4 : */
|