/* A colour difference operation.
*/
int
im__colour_difference( const char *domain,
IMAGE *in1, IMAGE *in2, IMAGE *out,
im_wrapmany_fn buffer_fn, void *a, void *b )
{
IMAGE *t[3];
if( im_check_uncoded( domain, in1 ) ||
im_check_uncoded( domain, in2 ) ||
im_check_bands( domain, in1, 3 ) ||
im_check_bands( domain, in2, 3 ) ||
im_check_size_same( domain, in1, in2 ) ||
im_open_local_array( out, t, 2, domain, "p" ) ||
im_clip2fmt( in1, t[0], IM_BANDFMT_FLOAT ) ||
im_clip2fmt( in2, t[1], IM_BANDFMT_FLOAT ) )
return( -1 );
if( im_cp_descv( out, t[0], t[1], NULL ) )
return( -1 );
out->Bands = 1;
out->Type = IM_TYPE_B_W;
t[2] = NULL;
if( im_wrapmany( t, out, buffer_fn, a, b ) )
return( -1 );
return( 0 );
}
/**
* im_hist_indexed:
* @index: input image
* @value: input image
* @out: output image
*
* Make a histogram of @value, but use image @index to pick the bins. In other
* words, element zero in @out contains the sum of all the pixels in @value
* whose corresponding pixel in @index is zero.
*
* @index must have just one band and be u8 or u16. @value must be
* non-complex. @out always has the same size and format as @value.
*
* This operation is useful in conjunction with im_label_regions(). You can
* use it to find the centre of gravity of blobs in an image, for example.
*
* See also: im_histgr(), im_label_regions().
*
* Returns: 0 on success, -1 on error
*/
int
im_hist_indexed( IMAGE *index, IMAGE *value, IMAGE *out )
{
int size; /* Length of hist */
Histogram *mhist;
VipsGenerateFn scanfn;
/* Check images. PIO from in, WIO to out.
*/
if( im_pincheck( index ) ||
im_pincheck( value ) ||
im_outcheck( out ) ||
im_check_uncoded( "im_hist_indexed", index ) ||
im_check_uncoded( "im_hist_indexed", value ) ||
im_check_noncomplex( "im_hist_indexed", value ) ||
im_check_size_same( "im_hist_indexed", index, value ) ||
im_check_u8or16( "im_hist_indexed", index ) ||
im_check_mono( "im_hist_indexed", index ) )
return( -1 );
/* Find the range of pixel values we must handle.
*/
if( index->BandFmt == IM_BANDFMT_UCHAR ) {
size = 256;
scanfn = hist_scan_uchar;
}
else {
size = 65536;
scanfn = hist_scan_ushort;
}
/* Build main hist we accumulate data in.
*/
if( !(mhist = hist_build( index, value, out, value->Bands, size )) )
return( -1 );
/* Accumulate data.
*/
if( vips_sink( index,
hist_start, scanfn, hist_stop, mhist, NULL ) ||
hist_write( out, mhist ) ) {
hist_free( mhist );
return( -1 );
}
hist_free( mhist );
return( 0 );
}
