/**
* im_ismonotonic:
* @lut: lookup-table to test
* @out: set non-zero if @lut is monotonic
*
* Test @lut for monotonicity. @out is set non-zero if @lut is monotonic.
*
* See also: im_tone_build_range().
*
* Returns: 0 on success, -1 on error
*/
int
im_ismonotonic( IMAGE *lut, int *out )
{
IMAGE *t[2];
INTMASK *mask;
double m;
if( im_check_hist( "im_ismonotonic", lut ) ||
im_open_local_array( lut, t, 2, "im_ismonotonic", "p" ) )
return( -1 );
if( lut->Xsize == 1 )
mask = im_create_imaskv( "im_ismonotonic", 1, 2, -1, 1 );
else
mask = im_create_imaskv( "im_ismonotonic", 2, 1, -1, 1 );
if( !(mask = im_local_imask( lut, mask )) )
return( -1 );
mask->offset = 128;
/* We want >=128 everywhere, ie. no -ve transitions.
*/
if( im_conv( lut, t[0], mask ) ||
im_moreeqconst( t[0], t[1], 128 ) ||
im_min( t[1], &m ) )
return( -1 );
*out = m;
return( 0 );
}
/* 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 );
}
