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Adds a first cut for region shrink mode

This commit is contained in:
Simon Harris 2018-03-28 21:59:17 +11:00
parent 5578347c19
commit a14f3acdf5
3 changed files with 80 additions and 0 deletions
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2
libvips/include/vips/region.h
View File

@ -59,12 +59,14 @@ extern "C" {
* VipsRegionShrink:
* @VIPS_REGION_SHRINK_MEAN: use the average
* @VIPS_REGION_SHRINK_MEDIAN: use the median
* @VIPS_REGION_SHRINK_MODE: use the mode
*
* How to calculate the output pixels when shrinking a 2x2 region.
*/
typedef enum {
VIPS_REGION_SHRINK_MEAN,
VIPS_REGION_SHRINK_MEDIAN,
VIPS_REGION_SHRINK_MODE,
VIPS_REGION_SHRINK_LAST
} VipsRegionShrink;

1
libvips/iofuncs/enumtypes.c
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@ -876,6 +876,7 @@ vips_region_shrink_get_type( void )
static const GEnumValue values[] = {
{VIPS_REGION_SHRINK_MEAN, "VIPS_REGION_SHRINK_MEAN", "mean"},
{VIPS_REGION_SHRINK_MEDIAN, "VIPS_REGION_SHRINK_MEDIAN", "median"},
{VIPS_REGION_SHRINK_MODE, "VIPS_REGION_SHRINK_MODE", "mode"},
{VIPS_REGION_SHRINK_LAST, "VIPS_REGION_SHRINK_LAST", "last"},
{0, NULL, NULL}
};

77
libvips/iofuncs/region.c
View File

@ -1233,6 +1233,36 @@ vips_region_shrink_labpack( VipsRegion *from,
q += ps; \
}
/* This method is implemented so as to perform well and to always select an
* output pixel from one of the input pixels. As such we make only the
* following guarantees:
*
* ONLY works for non-complex uncoded images pixel types
* ALWAYS draws from the input values
* NEVER interpolates
* NOT stable with respect to the ordered set of input values
* IS stable with respect to the initial arrangement of input values
*/
#define SHRINK_TYPE_MODE( TYPE ) \
for( x = 0; x < target->width; x++ ) { \
TYPE *tp = (TYPE *) p; \
TYPE *tp1 = (TYPE *) (p + ls); \
TYPE *tq = (TYPE *) q; \
\
for( z = 0; z < nb; z++ ) { \
TYPE v[] = {tp[z], tp[z + nb], tp1[z], tp1[z + nb]}; \
int b0 = (v[0] == v[1]) | (v[0] == v[2]) | (v[0] == v[3]); \
int b1 = (v[1] == v[0]) | (v[1] == v[2]) | (v[1] == v[3]); \
int index = ((~b0) & 0x1) + (~(b0 ^ b1) & 0x1); \
tq[z] = v[index]; \
} \
\
/* Move on two pels in input. \
*/ \
p += ps << 1; \
q += ps; \
}
/* Generate area @target in @to using pixels in @from. Non-complex.
*/
static void
@ -1321,6 +1351,50 @@ vips_region_shrink_uncoded_median( VipsRegion *from,
}
}
/* Generate area @target in @to using pixels in @from. Non-complex.
*/
static void
vips_region_shrink_uncoded_mode( VipsRegion *from,
VipsRegion *to, const VipsRect *target )
{
int ls = VIPS_REGION_LSKIP( from );
int ps = VIPS_IMAGE_SIZEOF_PEL( from->im );
int nb = from->im->Bands;
int x, y, z;
for( y = 0; y < target->height; y++ ) {
VipsPel *p = VIPS_REGION_ADDR( from,
target->left * 2, (target->top + y) * 2 );
VipsPel *q = VIPS_REGION_ADDR( to,
target->left, target->top + y );
/* Process this line of pels.
*/
switch( from->im->BandFmt ) {
case VIPS_FORMAT_UCHAR:
SHRINK_TYPE_MODE( unsigned char ); break;
case VIPS_FORMAT_CHAR:
SHRINK_TYPE_MODE( signed char ); break;
case VIPS_FORMAT_USHORT:
SHRINK_TYPE_MODE( unsigned short ); break;
case VIPS_FORMAT_SHORT:
SHRINK_TYPE_MODE( signed short ); break;
case VIPS_FORMAT_UINT:
SHRINK_TYPE_MODE( unsigned int ); break;
case VIPS_FORMAT_INT:
SHRINK_TYPE_MODE( signed int ); break;
case VIPS_FORMAT_FLOAT:
SHRINK_TYPE_MODE( float ); break;
case VIPS_FORMAT_DOUBLE:
SHRINK_TYPE_MODE( double ); break;
default:
g_assert_not_reached();
}
}
}
/* Generate area @target in @to using pixels in @from. Non-complex.
*/
static void
@ -1334,6 +1408,9 @@ vips_region_shrink_uncoded( VipsRegion *from,
case VIPS_REGION_SHRINK_MEDIAN:
vips_region_shrink_uncoded_median( from, to, target );
break;
case VIPS_REGION_SHRINK_MODE:
vips_region_shrink_uncoded_mode( from, to, target );
break;
default:
g_assert_not_reached();