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fix black background in transparent areas

This commit is contained in:
Benjamin Gilbert 2011-11-27 15:07:07 -05:00
parent 25733e7bb7
commit 73c3ea38d2
1 changed files with 44 additions and 22 deletions
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66
libvips/format/openslide.c
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@ -6,6 +6,8 @@
* *
* 26/11/11 * 26/11/11
* - initial version * - initial version
* 27/11/11
* - fix black background in transparent areas
*/ */
/* /*
@ -36,12 +38,18 @@
#include <string.h> #include <string.h>
#include <stdint.h> #include <stdint.h>
#include <stdlib.h>
#include <limits.h> #include <limits.h>
#include <openslide.h> #include <openslide.h>
#include <vips/vips.h> #include <vips/vips.h>
#include <vips/intl.h> #include <vips/intl.h>
typedef struct {
openslide_t *osr;
uint32_t background;
} ReadSlide;
static void static void
close_slide( VipsImage *image, openslide_t *osr ) close_slide( VipsImage *image, openslide_t *osr )
{ {
@ -70,10 +78,10 @@ load_header( openslide_t *osr, VipsImage *out )
} }
static int static int
fill_region( VipsRegion *out, void *seq, void *_osr, void *unused, fill_region( VipsRegion *out, void *seq, void *_rslide, void *unused,
gboolean *stop ) gboolean *stop )
{ {
openslide_t *osr = _osr; ReadSlide *rslide = _rslide;
uint32_t *buf; uint32_t *buf;
const char *error; const char *error;
PEL *pel; PEL *pel;
@ -83,32 +91,34 @@ fill_region( VipsRegion *out, void *seq, void *_osr, void *unused,
buf = vips_malloc( NULL, out->valid.width * out->valid.height * buf = vips_malloc( NULL, out->valid.width * out->valid.height *
sizeof( *buf )); sizeof( *buf ));
openslide_read_region( osr, buf, out->valid.left, out->valid.top, openslide_read_region( rslide->osr, buf, out->valid.left,
0, out->valid.width, out->valid.height ); out->valid.top, 0, out->valid.width, out->valid.height );
for( y = 0; y < out->valid.height; y++ ) { for( y = 0; y < out->valid.height; y++ ) {
for( x = 0; x < out->valid.width; x++ ) { for( x = 0; x < out->valid.width; x++ ) {
/* Convert from ARGB to RGBA and undo /* Convert from ARGB to RGBA and undo
* premultiplication. * premultiplication.
*/ */
sample = buf[y * out->valid.height + x];
a = sample >> 24;
if( a == 0 ) {
/* R, G, B should also be zero, so we just
* need to avoid the zero divide.
*/
a = 1;
}
pel = VIPS_REGION_ADDR( out, out->valid.left + x, pel = VIPS_REGION_ADDR( out, out->valid.left + x,
out->valid.top + y ); out->valid.top + y );
pel[0] = 255 * ((sample >> 16) & 255) / a; sample = buf[y * out->valid.height + x];
pel[1] = 255 * ((sample >> 8) & 255) / a; a = sample >> 24;
pel[2] = 255 * (sample & 255) / a; if( a != 0 ) {
pel[0] = 255 * ((sample >> 16) & 255) / a;
pel[1] = 255 * ((sample >> 8) & 255) / a;
pel[2] = 255 * (sample & 255) / a;
} else {
/* Use background color.
*/
pel[0] = (rslide->background >> 16) & 255;
pel[1] = (rslide->background >> 8) & 255;
pel[2] = rslide->background & 255;
}
pel[3] = a; pel[3] = a;
} }
} }
vips_free( buf ); vips_free( buf );
error = openslide_get_error( osr ); error = openslide_get_error( rslide->osr );
if( error ) { if( error ) {
vips_error( "im_openslide2vips", _( "reading region: %s" ), vips_error( "im_openslide2vips", _( "reading region: %s" ),
error ); error );
@ -155,19 +165,31 @@ openslide2vips_header( const char *filename, VipsImage *out )
static int static int
im_openslide2vips( const char *filename, VipsImage *out ) im_openslide2vips( const char *filename, VipsImage *out )
{ {
openslide_t *osr; ReadSlide *rslide;
const char *background;
osr = openslide_open( filename ); rslide = VIPS_NEW( out, ReadSlide );
if( osr == NULL ) {
rslide->osr = openslide_open( filename );
if( rslide->osr == NULL ) {
vips_error( "im_openslide2vips", _( "failure opening slide" )); vips_error( "im_openslide2vips", _( "failure opening slide" ));
return( -1 ); return( -1 );
} }
g_signal_connect( out, "close", G_CALLBACK( close_slide ), osr ); g_signal_connect( out, "close", G_CALLBACK( close_slide ),
rslide->osr );
if( load_header( osr, out ) || vips_image_pio_output( out )) background = openslide_get_property_value( rslide->osr,
OPENSLIDE_PROPERTY_NAME_BACKGROUND_COLOR );
if( background != NULL )
rslide->background = strtoul( background, NULL, 16 );
else
rslide->background = 0xffffff;
if( load_header( rslide->osr, out ) || vips_image_pio_output( out ))
return( -1 ); return( -1 );
vips_demand_hint( out, VIPS_DEMAND_STYLE_SMALLTILE, NULL ); vips_demand_hint( out, VIPS_DEMAND_STYLE_SMALLTILE, NULL );
return vips_image_generate( out, NULL, fill_region, NULL, osr, NULL ); return vips_image_generate( out, NULL, fill_region, NULL, rslide,
NULL );
} }
static int static int