/**
* 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 );
}
/**
* im_gradient:
* @in: input image
* @out: output image
* @mask: convolution mask
*
* @in is convolved with @mask and with @mask after a 90 degree rotation. The
* result is the sum of the absolute value of the two convolutions.
*
* See also: im_lindetect(), im_gradient(), im_conv().
*
* Returns: 0 on success, -1 on error
*/
int
im_gradient( IMAGE *in, IMAGE *out, INTMASK *mask )
{
IMAGE *t[4];
INTMASK *rmask;
if( im_open_local_array( out, t, 4, "im_gradient", "p" ) )
return( -1 );
if( !(rmask = im_local_imask( out,
im_rotate_imask90( mask, mask->filename ) )) )
return( -1 );
if( im_conv( in, t[0], mask ) ||
im_conv( in, t[1], rmask ) ||
im_abs( t[0], t[2] ) ||
im_abs( t[1], t[3] ) ||
im_add( t[2], t[3], out ) )
return( -1 );
return( 0 );
}
/**
* im_lindetect:
* @in: input image
* @out: output image
* @mask: convolution mask
*
* @in is convolved four times with @mask, each time @mask is rotated by 45
* degrees. Each output pixel is the largest absolute value of the four
* convolutions.
*
* See also: im_compass(), im_gradient(), im_conv().
*
* Returns: 0 on success, -1 on error
*/
int
im_lindetect( IMAGE *in, IMAGE *out, INTMASK *mask )
{
IMAGE *filtered[4];
IMAGE *absed[4];
int i;
if( im_open_local_array( out, filtered, 4, "im_lindetect:1", "p" ) ||
im_open_local_array( out, absed, 4, "im_lindetect:2", "p" ) )
return( -1 );
for( i = 0; i < 4; i++ ) {
if( im_conv( in, filtered[i], mask ) ||
!(mask = im_local_imask( out,
im_rotate_imask45( mask, mask->filename ) )) )
return( -1 );
}
for( i = 0; i < 4; i++ )
if( im_abs( filtered[i], absed[i] ) )
return( -1 );
return( im_maxvalue( absed, out, 4 ) );
}
