seems to work
add @centre option for downsampling, see https://github.com/jcupitt/libvips/issues/504
This commit is contained in:
John Cupitt
parent
1e9cdef615
commit
d3cafb3a9f
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@ -43,6 +43,8 @@
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rounding down, thanks ioquatix
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- better support for tile overlaps in google maps mode in dzsave
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- dzsave puts vips-properties.xml in the main dir for gm and zoomify layouts
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- resize and reduce have @centre option for centre convention downsampling
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- vipsthumbnail uses centre convention to better match imagemagick
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19/8/16 started 8.3.4
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- better transparency handling in gifload, thanks diegocsandrim
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8
TODO
8
TODO
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@ -1,11 +1,3 @@
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- test possible centre hack
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I think we're moving too far ... this is going to shift the mask by 50%, we
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just want half a pixel
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put the shift into vips_reduce_make_mask() so it gets picked up by the double
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path too
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- not sure about utf8 error messages on win
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- strange:
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@ -4,6 +4,8 @@
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* - from shrink.c
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* 15/8/16
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* - rename xshrink -> hshrink for greater consistency
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* 9/9/16
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* - add @centre option
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*/
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/*
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@ -75,6 +77,10 @@ typedef struct _VipsReduce {
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*/
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VipsKernel kernel;
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/* Use centre rather than corner sampling convention.
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*/
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gboolean centre;
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} VipsReduce;
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typedef VipsResampleClass VipsReduceClass;
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@ -94,9 +100,11 @@ vips_reduce_build( VipsObject *object )
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if( vips_reducev( resample->in, &t[0], reduce->vshrink,
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"kernel", reduce->kernel,
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"centre", reduce->centre,
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NULL ) ||
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vips_reduceh( t[0], &t[1], reduce->hshrink,
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"kernel", reduce->kernel,
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"centre", reduce->centre,
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NULL ) ||
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vips_image_write( t[1], resample->out ) )
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return( -1 );
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@ -143,6 +151,13 @@ vips_reduce_class_init( VipsReduceClass *class )
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G_STRUCT_OFFSET( VipsReduce, kernel ),
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VIPS_TYPE_KERNEL, VIPS_KERNEL_LANCZOS3 );
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VIPS_ARG_BOOL( class, "centre", 7,
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_( "Centre" ),
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_( "Use centre sampling convention" ),
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VIPS_ARGUMENT_OPTIONAL_INPUT,
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G_STRUCT_OFFSET( VipsReduce, centre ),
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FALSE );
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/* The old names .. now use h and v everywhere.
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*/
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VIPS_ARG_DOUBLE( class, "xshrink", 8,
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@ -178,10 +193,14 @@ vips_reduce_init( VipsReduce *reduce )
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* Optional arguments:
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*
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* * @kernel: #VipsKernel to use to interpolate (default: lanczos3)
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* * @centre: %gboolean use centre rather than corner sampling convention
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*
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* Reduce @in by a pair of factors with a pair of 1D kernels. This
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* will not work well for shrink factors greater than three.
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*
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* Set @centre to use centre rather than corner sampling convention. Centre
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* convention can be useful to match the behaviour of other systems.
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*
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* This is a very low-level operation: see vips_resize() for a more
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* convenient way to resize images.
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*
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@ -6,6 +6,8 @@
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* - add other kernels
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* 15/8/16
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* - rename xshrink as hshrink for consistency
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* 9/9/16
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* - add @centre option
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*/
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/*
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@ -321,6 +323,8 @@ vips_reduceh_gen( VipsRegion *out_region, void *seq,
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s.top = r->top;
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s.width = r->width * reduceh->hshrink + reduceh->n_point;
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s.height = r->height;
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if( reduceh->centre )
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s.width += 1;
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if( vips_region_prepare( ir, &s ) )
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return( -1 );
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@ -335,6 +339,8 @@ vips_reduceh_gen( VipsRegion *out_region, void *seq,
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q = VIPS_REGION_ADDR( out_region, r->left, r->top + y );
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X = r->left * reduceh->hshrink;
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if( reduceh->centre )
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X += 0.5;
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/* We want p0 to be the start (ie. x == 0) of the input
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* scanline we are reading from. We can then calculate the p we
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@ -439,6 +445,7 @@ vips_reduceh_build( VipsObject *object )
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vips_object_local_array( object, 2 );
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VipsImage *in;
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int width;
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if( VIPS_OBJECT_CLASS( vips_reduceh_parent_class )->build( object ) )
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return( -1 );
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@ -465,8 +472,6 @@ vips_reduceh_build( VipsObject *object )
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return( -1 );
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}
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for( int x = 0; x < VIPS_TRANSFORM_SCALE + 1; x++ ) {
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float fx;
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reduceh->matrixf[x] =
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VIPS_ARRAY( object, reduceh->n_point, double );
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reduceh->matrixi[x] =
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@ -475,18 +480,9 @@ vips_reduceh_build( VipsObject *object )
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!reduceh->matrixi[x] )
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return( -1 );
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/* Calculate our [0, 1] float displacement. For centre
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* convention we must shift by 0.5 and wrap around.
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*/
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fx = (float) x / VIPS_TRANSFORM_SCALE;
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if( reduceh->centre ) {
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fx += 0.5;
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if( fx > 1.0 )
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fx -= 1.0;
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}
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vips_reduce_make_mask( reduceh->matrixf[x],
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reduceh->kernel, reduceh->hshrink, fx );
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reduceh->kernel, reduceh->hshrink,
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(float) x / VIPS_TRANSFORM_SCALE );
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for( int i = 0; i < reduceh->n_point; i++ )
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reduceh->matrixi[x][i] = reduceh->matrixf[x][i] *
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@ -500,10 +496,15 @@ vips_reduceh_build( VipsObject *object )
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in = t[0];
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/* Add new pixels around the input so we can interpolate at the edges.
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* In centre mode, we read 0.5 pixels more to the right, so we must
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* enlarge a little further.
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*/
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width = in->Xsize + reduceh->n_point - 1;
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if( reduceh->centre )
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width += 1;
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if( vips_embed( in, &t[1],
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reduceh->n_point / 2 - 1, 0,
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in->Xsize + reduceh->n_point - 1, in->Ysize,
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width, in->Ysize,
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"extend", VIPS_EXTEND_COPY,
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NULL ) )
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return( -1 );
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@ -521,7 +522,7 @@ vips_reduceh_build( VipsObject *object )
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* fractional part), we just see the integer part here.
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*/
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resample->out->Xsize = VIPS_ROUND_UINT(
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(in->Xsize - reduceh->n_point + 1) / reduceh->hshrink );
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resample->in->Xsize / reduceh->hshrink );
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if( resample->out->Xsize <= 0 ) {
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vips_error( object_class->nickname,
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"%s", _( "image has shrunk to nothing" ) );
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@ -13,6 +13,8 @@
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* - better accuracy with smarter multiplication
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* 15/8/16
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* - rename yshrink as vshrink for consistency
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* 9/9/16
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* - add @centre option
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*/
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/*
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@ -100,6 +102,10 @@ typedef struct _VipsReducev {
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*/
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VipsKernel kernel;
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/* Use centre rather than corner sampling convention.
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*/
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gboolean centre;
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/* Number of points in kernel.
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*/
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int n_point;
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@ -526,6 +532,8 @@ vips_reducev_gen( VipsRegion *out_region, void *vseq,
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s.top = r->top * reducev->vshrink;
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s.width = r->width;
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s.height = r->height * reducev->vshrink + reducev->n_point;
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if( reducev->centre )
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s.height += 1;
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if( vips_region_prepare( ir, &s ) )
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return( -1 );
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@ -534,7 +542,8 @@ vips_reducev_gen( VipsRegion *out_region, void *vseq,
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for( int y = 0; y < r->height; y ++ ) {
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VipsPel *q =
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VIPS_REGION_ADDR( out_region, r->left, r->top + y );
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const double Y = (r->top + y) * reducev->vshrink;
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const double Y = (r->top + y) * reducev->vshrink +
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(reducev->centre ? 0.5 : 0.0);
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VipsPel *p = VIPS_REGION_ADDR( ir, r->left, (int) Y );
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const int sy = Y * VIPS_TRANSFORM_SCALE * 2;
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const int siy = sy & (VIPS_TRANSFORM_SCALE * 2 - 1);
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@ -636,6 +645,8 @@ vips_reducev_vector_gen( VipsRegion *out_region, void *vseq,
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s.top = r->top * reducev->vshrink;
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s.width = r->width;
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s.height = r->height * reducev->vshrink + reducev->n_point;
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if( reducev->centre )
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s.height += 1;
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if( vips_region_prepare( ir, &s ) )
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return( -1 );
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@ -653,7 +664,8 @@ vips_reducev_vector_gen( VipsRegion *out_region, void *vseq,
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for( int y = 0; y < r->height; y ++ ) {
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VipsPel *q =
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VIPS_REGION_ADDR( out_region, r->left, r->top + y );
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const double Y = (r->top + y) * reducev->vshrink;
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const double Y = (r->top + y) * reducev->vshrink +
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(reducev->centre ? 0.5 : 0.0);
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const int py = (int) Y;
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const int sy = Y * VIPS_TRANSFORM_SCALE * 2;
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const int siy = sy & (VIPS_TRANSFORM_SCALE * 2 - 1);
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@ -783,7 +795,7 @@ vips_reducev_raw( VipsReducev *reducev, VipsImage *in )
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* fractional part), we just see the integer part here.
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*/
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resample->out->Ysize = VIPS_ROUND_UINT(
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(in->Ysize - reducev->n_point + 1) / reducev->vshrink );
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resample->in->Ysize / reducev->vshrink );
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if( resample->out->Ysize <= 0 ) {
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vips_error( object_class->nickname,
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"%s", _( "image has shrunk to nothing" ) );
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@ -813,6 +825,7 @@ vips_reducev_build( VipsObject *object )
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VipsImage **t = (VipsImage **) vips_object_local_array( object, 2 );
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VipsImage *in;
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int height;
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if( VIPS_OBJECT_CLASS( vips_reducev_parent_class )->build( object ) )
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return( -1 );
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@ -845,9 +858,12 @@ vips_reducev_build( VipsObject *object )
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/* Add new pixels around the input so we can interpolate at the edges.
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*/
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height = in->Ysize + reducev->n_point - 1;
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if( reducev->centre )
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height += 1;
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if( vips_embed( in, &t[1],
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0, reducev->n_point / 2 - 1,
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in->Xsize, in->Ysize + reducev->n_point - 1,
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in->Xsize, height,
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"extend", VIPS_EXTEND_COPY,
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NULL ) )
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return( -1 );
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@ -893,6 +909,13 @@ vips_reducev_class_init( VipsReducevClass *reducev_class )
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G_STRUCT_OFFSET( VipsReducev, kernel ),
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VIPS_TYPE_KERNEL, VIPS_KERNEL_LANCZOS3 );
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VIPS_ARG_BOOL( reducev_class, "centre", 7,
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_( "Centre" ),
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_( "Use centre sampling convention" ),
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VIPS_ARGUMENT_OPTIONAL_INPUT,
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G_STRUCT_OFFSET( VipsReducev, centre ),
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FALSE );
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/* Old name.
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*/
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VIPS_ARG_DOUBLE( reducev_class, "yshrink", 3,
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@ -920,9 +943,13 @@ vips_reducev_init( VipsReducev *reducev )
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* Optional arguments:
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*
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* * @kernel: #VipsKernel to use to interpolate (default: lanczos3)
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* * @centre: %gboolean use centre rather than corner sampling convention
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*
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* Reduce @in vertically by a float factor. The pixels in @out are
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* interpolated with a 1D mask.
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* interpolated with a 1D mask generated by @kernel.
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*
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* Set @centre to use centre rather than corner sampling convention. Centre
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* convention can be useful to match the behaviour of other systems.
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*
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* This is a very low-level operation: see vips_resize() for a more
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* convenient way to resize images.
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@ -20,6 +20,8 @@
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* - faster and better upsizing
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* 15/8/16
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* - more accurate resizing
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* 9/9/16
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* - add @centre option
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*/
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/*
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@ -78,6 +80,7 @@ typedef struct _VipsResize {
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double scale;
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double vscale;
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VipsKernel kernel;
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gboolean centre;
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/* Deprecated.
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*/
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@ -252,6 +255,7 @@ vips_resize_build( VipsObject *object )
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vscale );
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if( vips_reducev( in, &t[2], 1.0 / vscale,
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"kernel", resize->kernel,
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"centre", resize->centre,
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NULL ) )
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return( -1 );
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in = t[2];
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@ -262,6 +266,7 @@ vips_resize_build( VipsObject *object )
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hscale );
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if( vips_reduceh( in, &t[3], 1.0 / hscale,
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"kernel", resize->kernel,
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"centre", resize->centre,
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NULL ) )
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return( -1 );
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in = t[3];
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@ -354,6 +359,13 @@ vips_resize_class_init( VipsResizeClass *class )
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G_STRUCT_OFFSET( VipsResize, kernel ),
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VIPS_TYPE_KERNEL, VIPS_KERNEL_LANCZOS3 );
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VIPS_ARG_BOOL( class, "centre", 7,
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_( "Centre" ),
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_( "Use centre sampling convention" ),
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VIPS_ARGUMENT_OPTIONAL_INPUT,
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G_STRUCT_OFFSET( VipsResize, centre ),
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FALSE );
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/* We used to let people set the input offset so you could pick centre
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* or corner interpolation, but it's not clear this was useful.
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*/
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@ -398,6 +410,7 @@ vips_resize_init( VipsResize *resize )
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*
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* * @vscale: %gdouble vertical scale factor
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* * @kernel: #VipsKernel to reduce with
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* * @centre: %gboolean use centre rather than corner sampling convention
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*
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* Resize an image.
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*
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@ -410,6 +423,9 @@ vips_resize_init( VipsResize *resize )
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* vips_resize() normally uses #VIPS_KERNEL_LANCZOS3 for the final reduce, you
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* can change this with @kernel.
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*
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* Set @centre to use centre rather than corner sampling convention. Centre
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* convention can be useful to match the behaviour of other systems.
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*
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* When upsizing (@scale > 1), the operation uses vips_affine() with
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* a #VipsInterpolate selected depending on @kernel. It will use
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* #VipsInterpolateBicubic for #VIPS_KERNEL_CUBIC and above.
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@ -450,7 +450,7 @@ thumbnail_shrink( VipsObject *process, VipsImage *in )
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shrink = calculate_shrink( in );
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if( vips_resize( in, &t[4], 1.0 / shrink, NULL ) )
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if( vips_resize( in, &t[4], 1.0 / shrink, "centre", TRUE, NULL ) )
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return( NULL );
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in = t[4];
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