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fix sizing issues with new reduce code

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a couple of bugs and some changed conventions
This commit is contained in:
John Cupitt 2016-03-13 17:44:24 +00:00
parent f12fef4aa9
commit fba2ac2f85
5 changed files with 16 additions and 19 deletions
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2
TODO
View File

@ -9,6 +9,8 @@
displacement error, I guess?
yes, reduceh output should move one to the right
- need more tests for reduce, test every kernel plus every numeric type
- try orc version of reducev? and shrinkv? maybe shrinkh?

8
libvips/resample/reduceh.cpp
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@ -496,7 +496,7 @@ vips_reduceh_build( VipsObject *object )
/* Add new pixels around the input so we can interpolate at the edges.
*/
if( vips_embed( in, &t[1],
reduceh->n_points / 2, 0,
reduceh->n_points / 2 - 1, 0,
in->Xsize + reduceh->n_points - 1, in->Ysize,
"extend", VIPS_EXTEND_COPY,
NULL ) )
@ -507,14 +507,14 @@ vips_reduceh_build( VipsObject *object )
VIPS_DEMAND_STYLE_THINSTRIP, in, NULL ) )
return( -1 );
/* Size output. Note: we round the output width down!
/* Size output. Note: we round to nearest to hide rounding errors.
*
* Don't change xres/yres, leave that to the application layer. For
* example, vipsthumbnail knows the true reduce factor (including the
* fractional part), we just see the integer part here.
*/
resample->out->Xsize = (in->Xsize - reduceh->n_points + 1) /
reduceh->xshrink;
resample->out->Xsize = VIPS_RINT(
(in->Xsize - reduceh->n_points + 1) / reduceh->xshrink );
if( resample->out->Xsize <= 0 ) {
vips_error( object_class->nickname,
"%s", _( "image has shrunk to nothing" ) );

7
libvips/resample/reducev.cpp
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@ -411,7 +411,7 @@ vips_reducev_build( VipsObject *object )
/* Add new pixels around the input so we can interpolate at the edges.
*/
if( vips_embed( in, &t[1],
0, reducev->n_points / 2,
0, reducev->n_points / 2 - 1,
in->Xsize, in->Ysize + reducev->n_points - 1,
"extend", VIPS_EXTEND_COPY,
NULL ) )
@ -422,13 +422,14 @@ vips_reducev_build( VipsObject *object )
VIPS_DEMAND_STYLE_SMALLTILE, in, NULL ) )
return( -1 );
/* Size output. Note: we round the output width down!
/* Size output. Note: we round to nearest to hide rounding errors.
*
* Don't change xres/yres, leave that to the application layer. For
* example, vipsthumbnail knows the true reduce factor (including the
* fractional part), we just see the integer part here.
*/
resample->out->Ysize = (in->Ysize - reducev->n_points + 1) / reducev->yshrink;
resample->out->Ysize = VIPS_RINT(
(in->Ysize - reducev->n_points + 1) / reducev->yshrink );
if( resample->out->Ysize <= 0 ) {
vips_error( object_class->nickname,
"%s", _( "image has shrunk to nothing" ) );

6
libvips/resample/resize.c
View File

@ -135,13 +135,11 @@ vips_resize_build( VipsObject *object )
/* Do we need a further size adjustment? It's the difference
* between our target size and the size we have after vips_shrink().
*
* Aim for a little above target so we can't round down below it.
*
* This can break the aspect ratio slightly :/ but hopefully no one
* will notice.
*/
hresidual = ((double) target_width + 0.1) / in->Xsize;
vresidual = ((double) target_height + 0.1) / in->Ysize;
hresidual = (double) target_width / in->Xsize;
vresidual = (double) target_height / in->Ysize;
/* We want to make sure we read the image sequentially.
* However, the convolution we may be doing later will force us

12
tools/vipsthumbnail.c
View File

@ -185,14 +185,13 @@ calculate_shrink( VipsImage *im )
VipsDirection direction;
/* Calculate the horizontal and vertical shrink we'd need to fit the
* image to the bounding box, and pick the biggest. Aim for a little
* above the target so we can't round down below it.
* image to the bounding box, and pick the biggest.
*
* In crop mode we aim to fill the bounding box, so we must use the
* smaller axis.
*/
double horizontal = (double) width / (thumbnail_width + 0.1);
double vertical = (double) height / (thumbnail_height + 0.1);
double horizontal = (double) width / thumbnail_width;
double vertical = (double) height / thumbnail_height;
if( crop_image ) {
if( horizontal < vertical )
@ -470,10 +469,7 @@ thumbnail_shrink( VipsObject *process, VipsImage *in )
shrink = calculate_shrink( in );
/* Add a tiny amount to stop rounding below the target.
*/
if( vips_resize( in, &t[4], 1.0 / shrink + 0.0000000001,
NULL ) )
if( vips_resize( in, &t[4], 1.0 / shrink, NULL ) )
return( NULL );
in = t[4];