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flatten alpha, bg default adjusts 

bg default adjusts to image type, thanks Kleis
This commit is contained in:
John Cupitt 2017-07-26 14:56:28 +01:00
parent 6359c92c01
commit 254e6a8b2a
1 changed files with 26 additions and 7 deletions
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33
libvips/arithmetic/find_trim.c
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@ -82,7 +82,22 @@ vips_find_trim_build( VipsObject *object )
if( VIPS_OBJECT_CLASS( vips_find_trim_parent_class )->build( object ) )
return( -1 );
if( vips_image_decode( find_trim->in, &t[0] ) )
/* Is "background" unset? Default to the correct value
* for this interpretation.
*/
if( !vips_object_argument_isset( object, "background" ) )
if( find_trim->in->Type == VIPS_INTERPRETATION_GREY16 ||
find_trim->in->Type == VIPS_INTERPRETATION_RGB16 ) {
vips_area_unref( VIPS_AREA( find_trim->background ) );
find_trim->background =
vips_array_double_newv( 1, 65535.0 );
}
/* Flatten out any alpha.
*/
if( vips_flatten( find_trim->in, &t[0],
"background", find_trim->background,
NULL ) )
return( -1 );
/* We want to subtract the bg.
@ -223,17 +238,21 @@ vips_find_trim_init( VipsFindTrim *find_trim )
* Optional arguments:
*
* * @threshold: %gdouble, background / object threshold
* * @background: #VipsArrayDouble, background colour, default 255
* * @background: #VipsArrayDouble, background colour
*
* Search @in for the bounding box of the non-background area.
*
* @in is median-filtered, then all the row and column sums of the absolute
* Any alpha is flattened out, then the image is median-filtered, all the row
* and column sums of the absolute
* difference from @background are calculated in a
* single pass through the image, then the first row or column in each of the
* four directions is found where the sum is greater than @threshold.
* single pass, then the first row or column in each of the
* four directions where the sum is greater than @threshold gives the bounding
* box.
*
* @background defaults to 255. Set another value, or use vips_getpoint() to
* pick a value from an edge. @threshold defaults to 10.
* @background defaults to 255, or 65535 for 16-bit images. Set another value,
* or use vips_getpoint() to pick a value from an edge.
*
* @threshold defaults to 10.
*
* See also: vips_getpoint(), vips_extract_area(), vips_smartcrop().
*