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Merge pull request #1159 from lovell/tiffread-premultiplied-alpha

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Unpremultiply TIFF with associated alpha channel
This commit is contained in:
John Cupitt 2018-11-17 10:59:39 +00:00 committed by GitHub
commit 572e37a314
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GPG Key ID: 4AEE18F83AFDEB23
1 changed files with 41 additions and 8 deletions
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49
libvips/foreign/tiff2vips.c
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@ -247,6 +247,7 @@ typedef struct _RtiffHeader {
int sample_format;
gboolean separate;
int orientation;
gboolean premultiplied;
/* Result of TIFFIsTiled().
*/
@ -1692,6 +1693,29 @@ rtiff_autorotate( Rtiff *rtiff, VipsImage *in, VipsImage **out )
return( 0 );
}
/* Unpremultiply associative alpha, if any.
*/
static int
rtiff_unpremultiply( Rtiff *rtiff, VipsImage *in, VipsImage **out )
{
if( rtiff->header.premultiplied ) {
VipsImage *x;
if( vips_unpremultiply( in, &x, NULL ) ||
vips_cast( x, out, in->BandFmt, NULL ) ) {
g_object_unref( x );
return( -1 );
}
g_object_unref( x );
}
else {
*out = in;
g_object_ref( in );
}
return( 0 );
}
/* Tile-type TIFF reader core - pass in a per-tile transform. Generate into
* the im and do it all partially.
*/
@ -1701,7 +1725,7 @@ rtiff_read_tilewise( Rtiff *rtiff, VipsImage *out )
int tile_width = rtiff->header.tile_width;
int tile_height = rtiff->header.tile_height;
VipsImage **t = (VipsImage **)
vips_object_local_array( VIPS_OBJECT( out ), 3 );
vips_object_local_array( VIPS_OBJECT( out ), 4 );
#ifdef DEBUG
printf( "tiff2vips: rtiff_read_tilewise\n" );
@ -1755,11 +1779,10 @@ rtiff_read_tilewise( Rtiff *rtiff, VipsImage *out )
"tile_width", tile_width,
"tile_height", tile_height,
"max_tiles", 2 * (1 + t[0]->Xsize / tile_width),
NULL ) )
return( -1 );
if( rtiff_autorotate( rtiff, t[1], &t[2] ) )
return( -1 );
if( vips_image_write( t[2], out ) )
NULL ) ||
rtiff_autorotate( rtiff, t[1], &t[2] ) ||
rtiff_unpremultiply( rtiff, t[2], &t[3] ) ||
vips_image_write( t[3], out ) )
return( -1 );
return( 0 );
@ -1985,7 +2008,7 @@ static int
rtiff_read_stripwise( Rtiff *rtiff, VipsImage *out )
{
VipsImage **t = (VipsImage **)
vips_object_local_array( VIPS_OBJECT( out ), 3 );
vips_object_local_array( VIPS_OBJECT( out ), 4 );
#ifdef DEBUG
printf( "tiff2vips: rtiff_read_stripwise\n" );
@ -2070,7 +2093,9 @@ rtiff_read_stripwise( Rtiff *rtiff, VipsImage *out )
"tile_height", rtiff->header.rows_per_strip,
NULL ) ||
rtiff_autorotate( rtiff, t[1], &t[2] ) ||
vips_image_write( t[2], out ) )
rtiff_unpremultiply( rtiff, t[2], &t[3] ) ||
vips_image_write( t[3], out ) )
return( -1 );
return( 0 );
@ -2081,6 +2106,9 @@ rtiff_read_stripwise( Rtiff *rtiff, VipsImage *out )
static int
rtiff_header_read( Rtiff *rtiff, RtiffHeader *header )
{
uint16 extra_samples_count;
uint16 *extra_samples_types;
if( !tfget32( rtiff->tiff, TIFFTAG_IMAGEWIDTH, &header->width ) ||
!tfget32( rtiff->tiff, TIFFTAG_IMAGELENGTH, &header->height ) ||
!tfget16( rtiff->tiff,
@ -2184,6 +2212,11 @@ rtiff_header_read( Rtiff *rtiff, RtiffHeader *header )
header->tile_height = 0;
}
TIFFGetFieldDefaulted( rtiff->tiff, TIFFTAG_EXTRASAMPLES,
&extra_samples_count, &extra_samples_types );
header->premultiplied = extra_samples_count > 0 &&
extra_samples_types[0] == EXTRASAMPLE_ASSOCALPHA;
return( 0 );
}