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make premultiply n-band 

max_value should be a param as well?
This commit is contained in:
John Cupitt 2015-05-08 14:57:49 +01:00
parent 472bf7dbc3
commit b5944ef464
1 changed files with 13 additions and 40 deletions
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53
libvips/conversion/premultiply.c
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@ -63,26 +63,27 @@ typedef VipsConversionClass VipsPremultiplyClass;
G_DEFINE_TYPE( VipsPremultiply, vips_premultiply, VIPS_TYPE_CONVERSION );
/* Premultiply a greyscale (two band) image.
/* Premultiply an n-band image.
*/
#define PRE_GREY( IN, OUT ) { \
#define PRE_MANY( IN, OUT ) { \
IN * restrict p = (IN *) in; \
OUT * restrict q = (OUT *) out; \
\
for( x = 0; x < width; x++ ) { \
IN alpha = p[1]; \
IN alpha = p[bands - 1]; \
int clip_alpha = VIPS_CLIP( 0, alpha, max_value ); \
double nalpha = (double) clip_alpha / max_value; \
\
q[0] = p[0] * nalpha; \
q[1] = alpha; \
for( b = 0; b < bands - 1; b++ ) \
q[b] = p[b] * nalpha; \
q[b] = alpha; \
\
p += 2; \
q += 2; \
p += bands; \
q += bands; \
} \
}
/* Premultiply an RGB (four band) image.
/* Special case for RGBA, it's very common.
*/
#define PRE_RGB( IN, OUT ) { \
IN * restrict p = (IN *) in; \
@ -103,37 +104,12 @@ G_DEFINE_TYPE( VipsPremultiply, vips_premultiply, VIPS_TYPE_CONVERSION );
} \
}
/* Premultiply a CMYK (five band) image.
*/
#define PRE_CMYK( IN, OUT ) { \
IN * restrict p = (IN *) in; \
OUT * restrict q = (OUT *) out; \
\
for( x = 0; x < width; x++ ) { \
IN alpha = p[4]; \
int clip_alpha = VIPS_CLIP( 0, alpha, max_value ); \
double nalpha = (double) clip_alpha / max_value; \
\
q[0] = p[0] * nalpha; \
q[1] = p[1] * nalpha; \
q[2] = p[2] * nalpha; \
q[3] = p[3] * nalpha; \
q[4] = alpha; \
\
p += 5; \
q += 5; \
} \
}
#define PRE( IN, OUT ) { \
if( bands == 2 ) { \
PRE_GREY( IN, OUT ); \
} \
else if( bands == 4 ) { \
if( bands == 3 ) { \
PRE_RGB( IN, OUT ); \
} \
else { \
PRE_CMYK( IN, OUT ); \
PRE_MANY( IN, OUT ); \
} \
}
@ -148,7 +124,7 @@ vips_premultiply_gen( VipsRegion *or, void *vseq, void *a, void *b,
int bands = im->Bands;
int max_value;
int x, y;
int x, y, b;
if( vips_region_prepare( ir, r ) )
return( -1 );
@ -229,10 +205,7 @@ vips_premultiply_build( VipsObject *object )
/* Trivial case: fall back to copy().
*/
if( in->Bands == 1 ||
in->Bands == 3 ||
(in->Bands == 4 &&
in->Type == VIPS_INTERPRETATION_CMYK) )
if( in->Bands == 1 )
return( vips_image_write( in, conversion->out ) );
if( vips_check_noncomplex( class->nickname, in ) )