/* Normalise an image using the rules noted above.
*/
static int
normalise( IMAGE *in, IMAGE *out )
{
if( im_check_uncoded( "im_histplot", in ) ||
im_check_noncomplex( "im_histplot", in ) )
return( -1 );
if( vips_bandfmt_isuint( in->BandFmt ) ) {
if( im_copy( in, out ) )
return( -1 );
}
else if( vips_bandfmt_isint( in->BandFmt ) ) {
IMAGE *t1;
double min;
/* Move min up to 0.
*/
if( !(t1 = im_open_local( out, "im_histplot", "p" )) ||
im_min( in, &min ) ||
im_lintra( 1.0, in, -min, t1 ) )
return( -1 );
}
else {
/* Float image: scale min--max to 0--any. Output square
* graph.
*/
IMAGE *t1;
DOUBLEMASK *stats;
double min, max;
int any;
if( in->Xsize == 1 )
any = in->Ysize;
else
any = in->Xsize;
if( !(stats = im_stats( in )) )
return( -1 );
min = VIPS_MASK( stats, 0, 0 );
max = VIPS_MASK( stats, 1, 0 );
im_free_dmask( stats );
if( !(t1 = im_open_local( out, "im_histplot", "p" )) ||
im_lintra( any / (max - min), in,
-min * any / (max - min), out ) )
return( -1 );
}
return( 0 );
}
/* Find stats on an area of an IMAGE ... consider only pixels for which the
* mask is true.
*/
static DOUBLEMASK *
find_image_stats( IMAGE *in, IMAGE *mask, Rect *area )
{
DOUBLEMASK *stats;
IMAGE *t[4];
gint64 count;
/* Extract area, build black image, mask out pixels we want.
*/
if( im_open_local_array( in, t, 4, "find_image_stats", "p" ) ||
extract_rect( in, t[0], area ) ||
im_black( t[1], t[0]->Xsize, t[0]->Ysize, t[0]->Bands ) ||
im_clip2fmt( t[1], t[2], t[0]->BandFmt ) ||
im_ifthenelse( mask, t[0], t[2], t[3] ) )
return( NULL );
/* Get stats from masked image.
*/
if( !(stats = local_mask( in, im_stats( t[3] ) )) )
return( NULL );
/* Number of non-zero pixels in mask.
*/
if( count_nonzero( mask, &count ) )
return( NULL );
/* And scale masked average to match.
*/
stats->coeff[4] *= (double) count /
((double) mask->Xsize * mask->Ysize);
/* Yuk! Zap the deviation column with the pixel count. Used later to
* determine if this is likely to be a significant overlap.
*/
stats->coeff[5] = count;
#ifdef DEBUG
if( count == 0 )
im_warn( "global_balance", _( "empty overlap!" ) );
#endif /*DEBUG*/
return( stats );
}
