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Remove round-to-nearest behaviour 

It seems that it generates the same image, with or without this change.

Tested with https://github.com/kleisauke/vips-issue-703.
This commit is contained in:
Kleis Auke Wolthuizen 2020-06-06 14:29:57 +02:00
parent c0ed106079
commit ac30bad695
3 changed files with 31 additions and 41 deletions
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25
libvips/resample/bicubic.cpp
View File

@ -79,16 +79,15 @@ typedef VipsInterpolate VipsInterpolateBicubic;
typedef VipsInterpolateClass VipsInterpolateBicubicClass;
/* Precalculated interpolation matrices. int (used for pel
* sizes up to short), and double (for all others). We go to
* scale + 1 so we can round-to-nearest safely.
* sizes up to short), and double (for all others).
*/
/* We could keep a large set of 2d 4x4 matricies, but this actually
* works out slower since for many resizes the thing will no longer
* fit in L1.
*/
static int vips_bicubic_matrixi[VIPS_TRANSFORM_SCALE + 1][4];
static double vips_bicubic_matrixf[VIPS_TRANSFORM_SCALE + 1][4];
static int vips_bicubic_matrixi[VIPS_TRANSFORM_SCALE][4];
static double vips_bicubic_matrixf[VIPS_TRANSFORM_SCALE][4];
/* We need C linkage for this.
*/
@ -498,19 +497,13 @@ static void
vips_interpolate_bicubic_interpolate( VipsInterpolate *interpolate,
void *out, VipsRegion *in, double x, double y )
{
/* Find the mask index. We round-to-nearest, so we need to generate
* indexes in 0 to VIPS_TRANSFORM_SCALE, 2^n + 1 values. We multiply
* by 2 more than we need to, add one, mask, then shift down again to
* get the extra range.
/* Find the mask index.
*/
const int sx = x * VIPS_TRANSFORM_SCALE * 2;
const int sy = y * VIPS_TRANSFORM_SCALE * 2;
const int sx = x * VIPS_TRANSFORM_SCALE;
const int sy = y * VIPS_TRANSFORM_SCALE;
const int six = sx & (VIPS_TRANSFORM_SCALE * 2 - 1);
const int siy = sy & (VIPS_TRANSFORM_SCALE * 2 - 1);
const int tx = (six + 1) >> 1;
const int ty = (siy + 1) >> 1;
const int tx = sx & (VIPS_TRANSFORM_SCALE - 1);
const int ty = sy & (VIPS_TRANSFORM_SCALE - 1);
/* We know x/y are always positive, so we can just (int) them.
*/
@ -643,7 +636,7 @@ vips_interpolate_bicubic_class_init( VipsInterpolateBicubicClass *iclass )
/* Build the tables of pre-computed coefficients.
*/
for( int x = 0; x < VIPS_TRANSFORM_SCALE + 1; x++ ) {
for( int x = 0; x < VIPS_TRANSFORM_SCALE; x++ ) {
calculate_coefficients_catmull( vips_bicubic_matrixf[x],
(float) x / VIPS_TRANSFORM_SCALE );

17
libvips/resample/reduceh.cpp
View File

@ -11,6 +11,7 @@
* 6/6/20 kleisauke
* - deprecate @centre option, it's now always on
* - fix pixel shift
* - remove unnecessary round-to-nearest behaviour
*/
/*
@ -78,11 +79,10 @@ typedef struct _VipsReduceh {
double hoffset;
/* Precalculated interpolation matrices. int (used for pel
* sizes up to short), and double (for all others). We go to
* scale + 1 so we can round-to-nearest safely.
* sizes up to short), and double (for all others).
*/
int *matrixi[VIPS_TRANSFORM_SCALE + 1];
double *matrixf[VIPS_TRANSFORM_SCALE + 1];
int *matrixi[VIPS_TRANSFORM_SCALE];
double *matrixf[VIPS_TRANSFORM_SCALE];
/* Deprecated.
*/
@ -320,7 +320,7 @@ vips_reduceh_gen( VipsRegion *out_region, void *seq,
VIPS_GATE_START( "vips_reduceh_gen: work" );
for( int y = 0; y < r->height; y ++ ) {
for( int y = 0; y < r->height; y++ ) {
VipsPel *p0;
VipsPel *q;
@ -346,9 +346,8 @@ vips_reduceh_gen( VipsRegion *out_region, void *seq,
for( int x = 0; x < r->width; x++ ) {
const int ix = (int) X;
VipsPel *p = p0 + ix * ps;
const int sx = X * VIPS_TRANSFORM_SCALE * 2;
const int six = sx & (VIPS_TRANSFORM_SCALE * 2 - 1);
const int tx = (six + 1) >> 1;
const int sx = X * VIPS_TRANSFORM_SCALE;
const int tx = sx & (VIPS_TRANSFORM_SCALE - 1);
const int *cxi = reduceh->matrixi[tx];
const double *cxf = reduceh->matrixf[tx];
@ -480,7 +479,7 @@ vips_reduceh_build( VipsObject *object )
/* Build the tables of pre-computed coefficients.
*/
for( int x = 0; x < VIPS_TRANSFORM_SCALE + 1; x++ ) {
for( int x = 0; x < VIPS_TRANSFORM_SCALE; x++ ) {
reduceh->matrixf[x] =
VIPS_ARRAY( object, reduceh->n_point, double );
reduceh->matrixi[x] =

30
libvips/resample/reducev.cpp
View File

@ -21,6 +21,7 @@
* - deprecate @centre option, it's now always on
* - fix pixel shift
* - speed up the mask construction for uchar/ushort images
* - remove unnecessary round-to-nearest behaviour
*/
/*
@ -117,15 +118,14 @@ typedef struct _VipsReducev {
double voffset;
/* Precalculated interpolation matrices. int (used for pel
* sizes up to short), and double (for all others). We go to
* scale + 1 so we can round-to-nearest safely.
* sizes up to short), and double (for all others).
*/
int *matrixi[VIPS_TRANSFORM_SCALE + 1];
double *matrixf[VIPS_TRANSFORM_SCALE + 1];
int *matrixi[VIPS_TRANSFORM_SCALE];
double *matrixf[VIPS_TRANSFORM_SCALE];
/* And another set for orc: we want 2.6 precision.
*/
int *matrixo[VIPS_TRANSFORM_SCALE + 1];
int *matrixo[VIPS_TRANSFORM_SCALE];
/* The passes we generate for this mask.
*/
@ -154,7 +154,7 @@ vips_reducev_finalize( GObject *gobject )
for( int i = 0; i < reducev->n_pass; i++ )
VIPS_FREEF( vips_vector_free, reducev->pass[i].vector );
reducev->n_pass = 0;
for( int i = 0; i < VIPS_TRANSFORM_SCALE + 1; i++ ) {
for( int i = 0; i < VIPS_TRANSFORM_SCALE; i++ ) {
VIPS_FREE( reducev->matrixf[i] );
VIPS_FREE( reducev->matrixi[i] );
VIPS_FREE( reducev->matrixo[i] );
@ -550,14 +550,13 @@ vips_reducev_gen( VipsRegion *out_region, void *vseq,
double Y = (r->top + 0.5) * reducev->vshrink - 0.5 -
reducev->voffset;
for( int y = 0; y < r->height; y ++ ) {
for( int y = 0; y < r->height; y++ ) {
VipsPel *q =
VIPS_REGION_ADDR( out_region, r->left, r->top + y );
const int py = (int) Y;
VipsPel *p = VIPS_REGION_ADDR( ir, r->left, py );
const int sy = Y * VIPS_TRANSFORM_SCALE * 2;
const int siy = sy & (VIPS_TRANSFORM_SCALE * 2 - 1);
const int ty = (siy + 1) >> 1;
const int sy = Y * VIPS_TRANSFORM_SCALE;
const int ty = sy & (VIPS_TRANSFORM_SCALE - 1);
const int *cyi = reducev->matrixi[ty];
const double *cyf = reducev->matrixf[ty];
const int lskip = VIPS_REGION_LSKIP( ir );
@ -675,13 +674,12 @@ vips_reducev_vector_gen( VipsRegion *out_region, void *vseq,
double Y = (r->top + 0.5) * reducev->vshrink - 0.5 -
reducev->voffset;
for( int y = 0; y < r->height; y ++ ) {
for( int y = 0; y < r->height; y++ ) {
VipsPel *q =
VIPS_REGION_ADDR( out_region, r->left, r->top + y );
const int py = (int) Y;
const int sy = Y * VIPS_TRANSFORM_SCALE * 2;
const int siy = sy & (VIPS_TRANSFORM_SCALE * 2 - 1);
const int ty = (siy + 1) >> 1;
const int sy = Y * VIPS_TRANSFORM_SCALE;
const int ty = sy & (VIPS_TRANSFORM_SCALE - 1);
const int *cyo = reducev->matrixo[ty];
#ifdef DEBUG_PIXELS
@ -742,7 +740,7 @@ vips_reducev_raw( VipsReducev *reducev, VipsImage *in, VipsImage **out )
*/
if( in->BandFmt == VIPS_FORMAT_UCHAR &&
vips_vector_isenabled() )
for( int y = 0; y < VIPS_TRANSFORM_SCALE + 1; y++ ) {
for( int y = 0; y < VIPS_TRANSFORM_SCALE; y++ ) {
reducev->matrixo[y] =
VIPS_ARRAY( NULL, reducev->n_point, int );
if( !reducev->matrixo[y] )
@ -854,7 +852,7 @@ vips_reducev_build( VipsObject *object )
/* Build the tables of pre-computed coefficients.
*/
for( int y = 0; y < VIPS_TRANSFORM_SCALE + 1; y++ ) {
for( int y = 0; y < VIPS_TRANSFORM_SCALE; y++ ) {
reducev->matrixf[y] =
VIPS_ARRAY( NULL, reducev->n_point, double );
reducev->matrixi[y] =