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builds half float mask

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This commit is contained in:
John Cupitt 2017-10-14 13:46:51 +01:00
parent ec99ff5000
commit 36f21138d7
1 changed files with 42 additions and 32 deletions
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74
libvips/convolution/convi.c
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@ -905,56 +905,32 @@ vips_convi_intize( VipsConvi *convi, VipsImage *M )
shift = ceil( log2( mx ) ); shift = ceil( log2( mx ) );
/* We need to sum n_points, so we have to shift right before adding a /* We need to sum n_points, so we have to shift right before adding a
* new value to make sure we have enough range. More than 8 bits of * new value to make sure we have enough range.
* shift means we would have less than 8 bits of precision in the final
* result.
*/ */
convi->sexp = ceil( log2( n_point ) ); convi->sexp = ceil( log2( n_point ) );
if( convi->sexp > 8 ) { if( convi->sexp > 10 ) {
g_info( "vips_convi_intize: mask too large" ); g_info( "vips_convi_intize: mask too large" );
return( -1 ); return( -1 );
} }
/* With that already done, the final shift must be ... /* With that already done, the final shift must be ...
*/ */
convi->exp = convi->sexp - shift; convi->exp = 7 - shift - convi->sexp;
if( (convi->mant = VIPS_ARRAY( convi, n_point, int )) ) if( !(convi->mant = VIPS_ARRAY( convi, n_point, int )) )
return( -1 ); return( -1 );
for( i = 0; i < n_point; i++ ) { for( i = 0; i < n_point; i++ ) {
convi->mant[i] = ((int) (256 * scaled[i])) >> shift; /* 128 since this is signed.
*/
convi->mant[i] = VIPS_RINT( 128 * scaled[i] * pow(2, -shift) );
if( convi->mant[i] < -128 || if( convi->mant[i] < -128 ||
convi->mant[i] > 128 ) { convi->mant[i] > 127 ) {
g_info( "vips_convi_intize: mask range too large" ); g_info( "vips_convi_intize: mask range too large" );
return( -1 ); return( -1 );
} }
} }
/* Verify accuracy.
*/
{
double true_sum;
int int_sum;
int true_value;
int int_value;
true_sum = 0.0;
int_sum = 0;
for( i = 0; i < n_point; i++ ) {
true_sum += 128 * scaled[i];
int_sum += (128 * convi->mant[i]) >> convi->sexp;
}
true_value = VIPS_CLIP( 0, true_sum, 255 );
int_value = VIPS_CLIP( 0, int_sum >> (convi->exp + 8), 255 );
if( VIPS_ABS( true_value - int_value ) > 20 ) {
g_info( "vips_convi_intize: too inaccurate" );
return( -1 );
}
}
#ifdef DEBUG_COMPILE #ifdef DEBUG_COMPILE
{ {
int x, y; int x, y;
@ -971,6 +947,40 @@ vips_convi_intize( VipsConvi *convi, VipsImage *M )
} }
#endif /*DEBUG_COMPILE*/ #endif /*DEBUG_COMPILE*/
/* Verify accuracy.
*/
{
double true_sum;
int int_sum;
int true_value;
int int_value;
true_sum = 0.0;
int_sum = 0;
for( i = 0; i < n_point; i++ ) {
int value;
true_sum += 128 * scaled[i];
value = 128 * convi->mant[i];
value = (value + (1 << (convi->sexp - 1))) >> convi->sexp;
int_sum += value;
int_sum = VIPS_CLIP( SHRT_MIN, int_sum, SHRT_MAX );
}
true_value = VIPS_CLIP( 0, true_sum, 255 );
if( convi->exp > 0 )
int_value = (int_sum + (1 << (convi->exp - 1))) >> convi->exp;
else
int_value = int_sum << convi->exp;
int_value = VIPS_CLIP( 0, int_value, 255 );
if( VIPS_ABS( true_value - int_value ) > 2 ) {
g_info( "vips_convi_intize: too inaccurate" );
return( -1 );
}
}
return( 0 ); return( 0 );
} }