switch to float distance calculations
removes dithering effects along edges
This commit is contained in:
John Cupitt
parent
cb37089c9b
commit
cdc286e9d6
@ -32,6 +32,7 @@
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- added vips_value_set_blob_free()
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- "--size Nx" to vipsthumbnail was broken, thanks jrochkind
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- fix build with gcc 7
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- add vips_nearest() ... fill pixels with nearest colour
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29/8/17 started 8.5.9
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- make --fail stop jpeg read on any libjpeg warning, thanks @mceachen
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@ -1,7 +1,7 @@
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/* nearest.c
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*
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* 31/10/17
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* - from labelregion and draw_circle
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* - from labelregion
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*/
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/*
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@ -31,7 +31,9 @@
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*/
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/*
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#define DEBUG
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*/
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#ifdef HAVE_CONFIG_H
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#include <config.h>
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@ -64,6 +66,11 @@ typedef struct _VipsNearest {
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VipsImage *out;
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VipsImage *distance;
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/* Size of our image.
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*/
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int width;
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int height;
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/* All our seed pixels. There can be a lot of these.
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*/
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GArray *seeds;
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@ -91,7 +98,7 @@ vips_nearest_finalize( GObject *gobject )
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struct _Circle;
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typedef void (*VipsNearestPixel)( struct _Circle *circle,
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int x, int y, int r, int octant );
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int x, int y, int octant );
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typedef struct _Circle {
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VipsNearest *nearest;
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@ -101,17 +108,24 @@ typedef struct _Circle {
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} Circle;
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static void
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vips_nearest_pixel( Circle *circle, int x, int y, int r, int octant )
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vips_nearest_pixel( Circle *circle, int x, int y, int octant )
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{
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guint *p;
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float *p;
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float radius;
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int dx, dy;
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if( (circle->seed->octant_mask & (1 << octant)) == 0 )
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return;
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p = (guint *) VIPS_IMAGE_ADDR( circle->nearest->distance, x, y );
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/* We need to do this as float, or we'll have dithering along edges.
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*/
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p = (float *) VIPS_IMAGE_ADDR( circle->nearest->distance, x, y );
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dx = x - circle->seed->x;
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dy = y - circle->seed->y;
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radius = sqrt( dx * dx + dy * dy );
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if( p[0] == 0 ||
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p[0] > r ) {
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p[0] > radius ) {
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VipsMorphology *morphology = VIPS_MORPHOLOGY( circle->nearest );
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VipsImage *in = morphology->in;
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int ps = VIPS_IMAGE_SIZEOF_PEL( in );
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@ -122,7 +136,7 @@ vips_nearest_pixel( Circle *circle, int x, int y, int r, int octant )
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int i;
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p[0] = r;
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p[0] = radius;
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circle->octant_mask |= 1 << octant;
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for( i = 0; i < ps; i++ )
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@ -131,16 +145,16 @@ vips_nearest_pixel( Circle *circle, int x, int y, int r, int octant )
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}
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static void
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vips_nearest_pixel_clip( Circle *circle, int x, int y, int r, int octant )
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vips_nearest_pixel_clip( Circle *circle, int x, int y, int octant )
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{
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if( (circle->seed->octant_mask & (1 << octant)) == 0 )
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return;
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if( y >= 0 &&
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y < circle->nearest->distance->Ysize &&
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x >= 0 &&
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x < circle->nearest->distance->Xsize )
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vips_nearest_pixel( circle, x, y, r, octant );
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if( x >= 0 &&
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x < circle->nearest->width &&
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y >= 0 &&
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y < circle->nearest->height )
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vips_nearest_pixel( circle, x, y, octant );
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}
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static void
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@ -149,29 +163,23 @@ vips_nearest_scanline( VipsImage *image,
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{
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Circle *circle = (Circle *) client;
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circle->nearest_pixel( circle, x1, y, circle->seed->r, quadrant );
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circle->nearest_pixel( circle, x2, y, circle->seed->r, quadrant + 4 );
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circle->nearest_pixel( circle, x1, y, quadrant );
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circle->nearest_pixel( circle, x2, y, quadrant + 4 );
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/* We have to do one point back as well, or we'll leave gaps at
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* around 45 degrees.
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*/
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if( quadrant == 0 ) {
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circle->nearest_pixel( circle,
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x1, y - 1, circle->seed->r - 1, quadrant );
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circle->nearest_pixel( circle,
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x2, y - 1, circle->seed->r - 1, quadrant + 4 );
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circle->nearest_pixel( circle, x1, y - 1, quadrant );
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circle->nearest_pixel( circle, x2, y - 1, quadrant + 4 );
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}
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else if( quadrant == 1 ) {
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circle->nearest_pixel( circle,
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x1, y + 1, circle->seed->r - 1, quadrant );
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circle->nearest_pixel( circle,
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x2, y + 1, circle->seed->r - 1, quadrant + 4 );
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circle->nearest_pixel( circle, x1, y + 1, quadrant );
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circle->nearest_pixel( circle, x2, y + 1, quadrant + 4 );
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}
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else {
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circle->nearest_pixel( circle,
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x1 + 1, y, circle->seed->r - 1, quadrant );
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circle->nearest_pixel( circle,
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x2 - 1, y, circle->seed->r - 1, quadrant + 4 );
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circle->nearest_pixel( circle, x1 + 1, y, quadrant );
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circle->nearest_pixel( circle, x2 - 1, y, quadrant + 4 );
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}
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}
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@ -185,9 +193,9 @@ vips_nearest_grow_seed( VipsNearest *nearest, Seed *seed )
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circle.octant_mask = 0;
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if( seed->x - seed->r >= 0 &&
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seed->x + seed->r < nearest->distance->Xsize &&
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seed->x + seed->r < nearest->width &&
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seed->y - seed->r >= 0 &&
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seed->y + seed->r < nearest->distance->Ysize )
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seed->y + seed->r < nearest->height )
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circle.nearest_pixel = vips_nearest_pixel;
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else
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circle.nearest_pixel = vips_nearest_pixel_clip;
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@ -209,7 +217,6 @@ vips_nearest_build( VipsObject *object )
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VipsMorphology *morphology = VIPS_MORPHOLOGY( object );
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VipsNearest *nearest = (VipsNearest *) object;
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VipsImage **t = (VipsImage **) vips_object_local_array( object, 2 );
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VipsImage *in = morphology->in;
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int ps;
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int x, y, i;
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@ -217,16 +224,18 @@ vips_nearest_build( VipsObject *object )
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if( VIPS_OBJECT_CLASS( vips_nearest_parent_class )->build( object ) )
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return( -1 );
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if( vips_image_wio_input( in ) )
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if( vips_image_wio_input( morphology->in ) )
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return( -1 );
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nearest->width = morphology->in->Xsize;
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nearest->height = morphology->in->Ysize;
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ps = VIPS_IMAGE_SIZEOF_PEL( in );
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ps = VIPS_IMAGE_SIZEOF_PEL( morphology->in );
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nearest->seeds = g_array_new( FALSE, FALSE, sizeof( Seed ) );
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for( y = 0; y < in->Ysize; y++ ) {
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for( y = 0; y < nearest->height; y++ ) {
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VipsPel *p;
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p = VIPS_IMAGE_ADDR( in, 0, y );
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for( x = 0; x < in->Xsize; x++ ) {
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p = VIPS_IMAGE_ADDR( morphology->in, 0, y );
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for( x = 0; x < nearest->width; x++ ) {
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for( i = 0; i < ps; i++ )
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if( p[i] )
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break;
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@ -251,13 +260,13 @@ vips_nearest_build( VipsObject *object )
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/* Create the output and distance images in memory.
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*/
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g_object_set( object, "distance", vips_image_new_memory(), NULL );
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if( vips_black( &t[1], in->Xsize, in->Ysize, NULL ) ||
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vips_cast( t[1], &t[2], VIPS_FORMAT_UINT, NULL ) ||
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if( vips_black( &t[1], nearest->width, nearest->height, NULL ) ||
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vips_cast( t[1], &t[2], VIPS_FORMAT_FLOAT, NULL ) ||
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vips_image_write( t[2], nearest->distance ) )
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return( -1 );
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g_object_set( object, "out", vips_image_new_memory(), NULL );
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if( vips_image_write( in, nearest->out ) )
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if( vips_image_write( morphology->in, nearest->out ) )
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return( -1 );
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while( nearest->seeds->len > 0 ) {
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@ -337,7 +346,7 @@ vips_nearest_init( VipsNearest *nearest )
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* the nearest non-zero pixel in @in, and @value contains the value of that
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* pixel.
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*
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* @distance is a one-band uint image. @value has the same number of bands and
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* @distance is a one-band float image. @value has the same number of bands and
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* format as @in.
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*
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* See also: vips_hist_find_indexed().
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