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fix mapim offsets

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pixels were not being offset by the stencil origin, so interpolators
like bicubic could fail

thanks @erdmann

https://github.com/libvips/libvips/issues/1180
This commit is contained in:
John Cupitt 2018-12-17 12:42:34 +00:00
parent 0d5eced964
commit db4fe60405
5 changed files with 28 additions and 12 deletions
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3
ChangeLog
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@ -1,3 +1,6 @@
17/12/18 started 8.7.4
- mapim was not offsetting by window offset [erdmann]
21/11/18 started 8.7.3
- fix infinite loop for autofit with non-scaleable font

6
configure.ac
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@ -2,7 +2,7 @@
# also update the version number in the m4 macros below
AC_INIT([vips], [8.7.3], [vipsip@jiscmail.ac.uk])
AC_INIT([vips], [8.7.4], [vipsip@jiscmail.ac.uk])
# required for gobject-introspection
AC_PREREQ(2.62)
@ -18,7 +18,7 @@ AC_CONFIG_MACRO_DIR([m4])
# user-visible library versioning
m4_define([vips_major_version], [8])
m4_define([vips_minor_version], [7])
m4_define([vips_micro_version], [3])
m4_define([vips_micro_version], [4])
m4_define([vips_version],
[vips_major_version.vips_minor_version.vips_micro_version])
@ -38,7 +38,7 @@ VIPS_VERSION_STRING=$VIPS_VERSION-`date -u -r ChangeLog`
# binary interface changes not backwards compatible?: reset age to 0
LIBRARY_CURRENT=51
LIBRARY_REVISION=3
LIBRARY_REVISION=4
LIBRARY_AGE=9
# patched into include/vips/version.h

10
libvips/resample/bicubic.cpp
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@ -533,17 +533,17 @@ vips_interpolate_bicubic_interpolate( VipsInterpolate *interpolate,
const int bands = in->im->Bands;
const int lskip = VIPS_REGION_LSKIP( in );
g_assert( ix - 1 >= in->valid.left );
g_assert( iy - 1 >= in->valid.top );
g_assert( ix + 2 < VIPS_RECT_RIGHT( &in->valid ) );
g_assert( iy + 2 < VIPS_RECT_BOTTOM( &in->valid ) );
/* Confirm that absolute_x and absolute_y are >= 1, because of
* window_offset.
*/
g_assert( x >= 1.0 );
g_assert( y >= 1.0 );
g_assert( ix - 1 >= in->valid.left );
g_assert( iy - 1 >= in->valid.top );
g_assert( ix + 2 < VIPS_RECT_RIGHT( &in->valid ) );
g_assert( iy + 2 < VIPS_RECT_BOTTOM( &in->valid ) );
#ifdef DEBUG
printf( "vips_interpolate_bicubic_interpolate: %g %g\n", x, y );
printf( "\tleft=%d, top=%d, width=%d, height=%d\n",

13
libvips/resample/mapim.c
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@ -5,6 +5,8 @@
* 12/8/18
* - prevent float->int overflow
* - a bit quicker
* 17/12/18
* - we were not offsetting pixel fetches by window_offset
*/
/*
@ -229,8 +231,8 @@ vips_mapim_region_minmax( VipsRegion *region, VipsRect *r, VipsRect *bounds )
TYPE * restrict p1 = (TYPE *) p; \
\
for( x = 0; x < r->width; x++ ) { \
TYPE px = p1[0]; \
TYPE py = p1[1]; \
TYPE px = p1[0] + window_offset; \
TYPE py = p1[1] + window_offset; \
\
if( px >= clip_width || \
py >= clip_height ) { \
@ -249,8 +251,8 @@ vips_mapim_region_minmax( VipsRegion *region, VipsRect *r, VipsRect *bounds )
TYPE * restrict p1 = (TYPE *) p; \
\
for( x = 0; x < r->width; x++ ) { \
TYPE px = p1[0]; \
TYPE py = p1[1]; \
TYPE px = p1[0] + window_offset; \
TYPE py = p1[1] + window_offset; \
\
if( px < 0 || \
px >= clip_width || \
@ -278,6 +280,8 @@ vips_mapim_gen( VipsRegion *or, void *seq, void *a, void *b, gboolean *stop )
const VipsImage *in = in_array[0];
const int window_size =
vips_interpolate_get_window_size( mapim->interpolate );
const int window_offset =
vips_interpolate_get_window_offset( mapim->interpolate );
const VipsInterpolateMethod interpolate =
vips_interpolate_get_method( mapim->interpolate );
const int ps = VIPS_IMAGE_SIZEOF_PEL( in );
@ -310,6 +314,7 @@ vips_mapim_gen( VipsRegion *or, void *seq, void *a, void *b, gboolean *stop )
/* The bounding box of that area is what we will need from @in. Add
* enough for the interpolation stencil as well.
*
*/
bounds.width += window_size - 1;
bounds.height += window_size - 1;

8
test/test-suite/test_resample.py
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@ -198,6 +198,14 @@ class TestResample:
b = im.crop(50, 0, im.width - 50, im.height).gaussblur(2)
assert (a - b).abs().max() < 20
# this was a bug at one point, strangely, if executed with debug
# enabled
mp = pyvips.Image.xyz(100, 100)
interp = pyvips.Interpolate.new('bicubic')
assert im.mapim(mp, interpolate=interp).avg() == \
im.crop(0, 0, 100, 100).avg()
if __name__ == '__main__':
pytest.main()