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switch to float distance calculations 

removes dithering effects along edges
This commit is contained in:
John Cupitt 2017-11-01 13:05:02 +00:00
parent cb37089c9b
commit cdc286e9d6
2 changed files with 49 additions and 39 deletions
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1
ChangeLog
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@ -32,6 +32,7 @@
- added vips_value_set_blob_free() - added vips_value_set_blob_free()
- "--size Nx" to vipsthumbnail was broken, thanks jrochkind - "--size Nx" to vipsthumbnail was broken, thanks jrochkind
- fix build with gcc 7 - fix build with gcc 7
- add vips_nearest() ... fill pixels with nearest colour
29/8/17 started 8.5.9 29/8/17 started 8.5.9
- make --fail stop jpeg read on any libjpeg warning, thanks @mceachen - make --fail stop jpeg read on any libjpeg warning, thanks @mceachen

87
libvips/morphology/nearest.c
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@ -1,7 +1,7 @@
/* nearest.c /* nearest.c
* *
* 31/10/17 * 31/10/17
* - from labelregion and draw_circle * - from labelregion
*/ */
/* /*
@ -31,7 +31,9 @@
*/ */
/*
#define DEBUG #define DEBUG
*/
#ifdef HAVE_CONFIG_H #ifdef HAVE_CONFIG_H
#include <config.h> #include <config.h>
@ -64,6 +66,11 @@ typedef struct _VipsNearest {
VipsImage *out; VipsImage *out;
VipsImage *distance; VipsImage *distance;
/* Size of our image.
*/
int width;
int height;
/* All our seed pixels. There can be a lot of these. /* All our seed pixels. There can be a lot of these.
*/ */
GArray *seeds; GArray *seeds;
@ -91,7 +98,7 @@ vips_nearest_finalize( GObject *gobject )
struct _Circle; struct _Circle;
typedef void (*VipsNearestPixel)( struct _Circle *circle, typedef void (*VipsNearestPixel)( struct _Circle *circle,
int x, int y, int r, int octant ); int x, int y, int octant );
typedef struct _Circle { typedef struct _Circle {
VipsNearest *nearest; VipsNearest *nearest;
@ -101,17 +108,24 @@ typedef struct _Circle {
} Circle; } Circle;
static void static void
vips_nearest_pixel( Circle *circle, int x, int y, int r, int octant ) vips_nearest_pixel( Circle *circle, int x, int y, int octant )
{ {
guint *p; float *p;
float radius;
int dx, dy;
if( (circle->seed->octant_mask & (1 << octant)) == 0 ) if( (circle->seed->octant_mask & (1 << octant)) == 0 )
return; return;
p = (guint *) VIPS_IMAGE_ADDR( circle->nearest->distance, x, y ); /* We need to do this as float, or we'll have dithering along edges.
*/
p = (float *) VIPS_IMAGE_ADDR( circle->nearest->distance, x, y );
dx = x - circle->seed->x;
dy = y - circle->seed->y;
radius = sqrt( dx * dx + dy * dy );
if( p[0] == 0 || if( p[0] == 0 ||
p[0] > r ) { p[0] > radius ) {
VipsMorphology *morphology = VIPS_MORPHOLOGY( circle->nearest ); VipsMorphology *morphology = VIPS_MORPHOLOGY( circle->nearest );
VipsImage *in = morphology->in; VipsImage *in = morphology->in;
int ps = VIPS_IMAGE_SIZEOF_PEL( in ); int ps = VIPS_IMAGE_SIZEOF_PEL( in );
@ -122,7 +136,7 @@ vips_nearest_pixel( Circle *circle, int x, int y, int r, int octant )
int i; int i;
p[0] = r; p[0] = radius;
circle->octant_mask |= 1 << octant; circle->octant_mask |= 1 << octant;
for( i = 0; i < ps; i++ ) for( i = 0; i < ps; i++ )
@ -131,16 +145,16 @@ vips_nearest_pixel( Circle *circle, int x, int y, int r, int octant )
} }
static void static void
vips_nearest_pixel_clip( Circle *circle, int x, int y, int r, int octant ) vips_nearest_pixel_clip( Circle *circle, int x, int y, int octant )
{ {
if( (circle->seed->octant_mask & (1 << octant)) == 0 ) if( (circle->seed->octant_mask & (1 << octant)) == 0 )
return; return;
if( y >= 0 && if( x >= 0 &&
y < circle->nearest->distance->Ysize && x < circle->nearest->width &&
x >= 0 && y >= 0 &&
x < circle->nearest->distance->Xsize ) y < circle->nearest->height )
vips_nearest_pixel( circle, x, y, r, octant ); vips_nearest_pixel( circle, x, y, octant );
} }
static void static void
@ -149,29 +163,23 @@ vips_nearest_scanline( VipsImage *image,
{ {
Circle *circle = (Circle *) client; Circle *circle = (Circle *) client;
circle->nearest_pixel( circle, x1, y, circle->seed->r, quadrant ); circle->nearest_pixel( circle, x1, y, quadrant );
circle->nearest_pixel( circle, x2, y, circle->seed->r, quadrant + 4 ); circle->nearest_pixel( circle, x2, y, quadrant + 4 );
/* We have to do one point back as well, or we'll leave gaps at /* We have to do one point back as well, or we'll leave gaps at
* around 45 degrees. * around 45 degrees.
*/ */
if( quadrant == 0 ) { if( quadrant == 0 ) {
circle->nearest_pixel( circle, circle->nearest_pixel( circle, x1, y - 1, quadrant );
x1, y - 1, circle->seed->r - 1, quadrant ); circle->nearest_pixel( circle, x2, y - 1, quadrant + 4 );
circle->nearest_pixel( circle,
x2, y - 1, circle->seed->r - 1, quadrant + 4 );
} }
else if( quadrant == 1 ) { else if( quadrant == 1 ) {
circle->nearest_pixel( circle, circle->nearest_pixel( circle, x1, y + 1, quadrant );
x1, y + 1, circle->seed->r - 1, quadrant ); circle->nearest_pixel( circle, x2, y + 1, quadrant + 4 );
circle->nearest_pixel( circle,
x2, y + 1, circle->seed->r - 1, quadrant + 4 );
} }
else { else {
circle->nearest_pixel( circle, circle->nearest_pixel( circle, x1 + 1, y, quadrant );
x1 + 1, y, circle->seed->r - 1, quadrant ); circle->nearest_pixel( circle, x2 - 1, y, quadrant + 4 );
circle->nearest_pixel( circle,
x2 - 1, y, circle->seed->r - 1, quadrant + 4 );
} }
} }
@ -185,9 +193,9 @@ vips_nearest_grow_seed( VipsNearest *nearest, Seed *seed )
circle.octant_mask = 0; circle.octant_mask = 0;
if( seed->x - seed->r >= 0 && if( seed->x - seed->r >= 0 &&
seed->x + seed->r < nearest->distance->Xsize && seed->x + seed->r < nearest->width &&
seed->y - seed->r >= 0 && seed->y - seed->r >= 0 &&
seed->y + seed->r < nearest->distance->Ysize ) seed->y + seed->r < nearest->height )
circle.nearest_pixel = vips_nearest_pixel; circle.nearest_pixel = vips_nearest_pixel;
else else
circle.nearest_pixel = vips_nearest_pixel_clip; circle.nearest_pixel = vips_nearest_pixel_clip;
@ -209,7 +217,6 @@ vips_nearest_build( VipsObject *object )
VipsMorphology *morphology = VIPS_MORPHOLOGY( object ); VipsMorphology *morphology = VIPS_MORPHOLOGY( object );
VipsNearest *nearest = (VipsNearest *) object; VipsNearest *nearest = (VipsNearest *) object;
VipsImage **t = (VipsImage **) vips_object_local_array( object, 2 ); VipsImage **t = (VipsImage **) vips_object_local_array( object, 2 );
VipsImage *in = morphology->in;
int ps; int ps;
int x, y, i; int x, y, i;
@ -217,16 +224,18 @@ vips_nearest_build( VipsObject *object )
if( VIPS_OBJECT_CLASS( vips_nearest_parent_class )->build( object ) ) if( VIPS_OBJECT_CLASS( vips_nearest_parent_class )->build( object ) )
return( -1 ); return( -1 );
if( vips_image_wio_input( in ) ) if( vips_image_wio_input( morphology->in ) )
return( -1 ); return( -1 );
nearest->width = morphology->in->Xsize;
nearest->height = morphology->in->Ysize;
ps = VIPS_IMAGE_SIZEOF_PEL( in ); ps = VIPS_IMAGE_SIZEOF_PEL( morphology->in );
nearest->seeds = g_array_new( FALSE, FALSE, sizeof( Seed ) ); nearest->seeds = g_array_new( FALSE, FALSE, sizeof( Seed ) );
for( y = 0; y < in->Ysize; y++ ) { for( y = 0; y < nearest->height; y++ ) {
VipsPel *p; VipsPel *p;
p = VIPS_IMAGE_ADDR( in, 0, y ); p = VIPS_IMAGE_ADDR( morphology->in, 0, y );
for( x = 0; x < in->Xsize; x++ ) { for( x = 0; x < nearest->width; x++ ) {
for( i = 0; i < ps; i++ ) for( i = 0; i < ps; i++ )
if( p[i] ) if( p[i] )
break; break;
@ -251,13 +260,13 @@ vips_nearest_build( VipsObject *object )
/* Create the output and distance images in memory. /* Create the output and distance images in memory.
*/ */
g_object_set( object, "distance", vips_image_new_memory(), NULL ); g_object_set( object, "distance", vips_image_new_memory(), NULL );
if( vips_black( &t[1], in->Xsize, in->Ysize, NULL ) || if( vips_black( &t[1], nearest->width, nearest->height, NULL ) ||
vips_cast( t[1], &t[2], VIPS_FORMAT_UINT, NULL ) || vips_cast( t[1], &t[2], VIPS_FORMAT_FLOAT, NULL ) ||
vips_image_write( t[2], nearest->distance ) ) vips_image_write( t[2], nearest->distance ) )
return( -1 ); return( -1 );
g_object_set( object, "out", vips_image_new_memory(), NULL ); g_object_set( object, "out", vips_image_new_memory(), NULL );
if( vips_image_write( in, nearest->out ) ) if( vips_image_write( morphology->in, nearest->out ) )
return( -1 ); return( -1 );
while( nearest->seeds->len > 0 ) { while( nearest->seeds->len > 0 ) {
@ -337,7 +346,7 @@ vips_nearest_init( VipsNearest *nearest )
* the nearest non-zero pixel in @in, and @value contains the value of that * the nearest non-zero pixel in @in, and @value contains the value of that
* pixel. * pixel.
* *
* @distance is a one-band uint image. @value has the same number of bands and * @distance is a one-band float image. @value has the same number of bands and
* format as @in. * format as @in.
* *
* See also: vips_hist_find_indexed(). * See also: vips_hist_find_indexed().