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better rounding in vipsthumbnail

This commit is contained in:
John Cupitt 2016-03-25 10:42:21 +00:00
parent 2996947b0d
commit 1a25c7a083
3 changed files with 31 additions and 19 deletions
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7
TODO
View File

@ -1,7 +1,8 @@
- test_thumbnail.sh is failing ... 1000->999 makes a 998 image
- check C++ API for new operations
- move 16->8 conversion to a separate pass? with so many constants, can't we
get an error for some mask sizes?
- check dosc for new ops, esp function list
- try make dist, check po
- try SEQ_UNBUFFERED on jpg source, get out of order error?

34
test/test_thumbnail.sh
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@ -8,11 +8,13 @@
. ./variables.sh
# make a 1000x1000 mono test image
# make a 1000x1000 mono test image ... add a bit so the image should not
# contain any zeros, helps to spot missing tiles and bad pixels
echo building test image ...
vips extract_band $image $tmp/t1.v 1
vips replicate $tmp/t1.v $tmp/t2.v 2 2
vips extract_area $tmp/t2.v $tmp/t1.v 10 10 1000 1000
vips linear $tmp/t1.v $tmp/t2.v 1 20 --uchar
vips replicate $tmp/t2.v $tmp/t1.v 2 2
vips crop $tmp/t1.v $tmp/t2.v 10 10 1000 1000
# is a difference beyond a threshold? return 0 (meaning all ok) or 1 (meaning
# error, or outside threshold)
@ -25,29 +27,35 @@ break_threshold() {
size=1000
while [ $size -gt 99 ]; do
printf "testing size to $size ... "
vipsthumbnail $tmp/t1.v -o $tmp/t2.v --size $size
if [ $(vipsheader -f width $tmp/t2.v) -ne $size ]; then
echo $tmp/t2.v failed -- bad size
echo output width is $(vipsheader -f width $tmp/t2.v)
vipsthumbnail $tmp/t2.v -o $tmp/t1.v --size $size
if [ $(vipsheader -f width $tmp/t1.v) -ne $size ]; then
echo $tmp/t1.v failed -- bad size
echo output width is $(vipsheader -f width $tmp/t1.v)
exit
fi
if [ $(vipsheader -f height $tmp/t2.v) -ne $size ]; then
echo $tmp/t2.v failed -- bad size
echo output height is $(vipsheader -f width $tmp/t2.v)
if [ $(vipsheader -f height $tmp/t1.v) -ne $size ]; then
echo $tmp/t1.v failed -- bad size
echo output height is $(vipsheader -f width $tmp/t1.v)
exit
fi
vips project $tmp/t2.v $tmp/cols.v $tmp/rows.v
vips project $tmp/t1.v $tmp/cols.v $tmp/rows.v
min=$(vips min $tmp/cols.v)
if break_threshold $min 0; then
echo $tmp/t2.v failed -- has a black column
echo $tmp/t1.v failed -- has a black column
exit
fi
min=$(vips min $tmp/rows.v)
if break_threshold $min 0; then
echo $tmp/t2.v failed -- has a black row
echo $tmp/t1.v failed -- has a black row
exit
fi
min=$(vips min $tmp/t1.v)
if break_threshold $min 0; then
echo $tmp/t1.v failed -- has black pixels
exit
fi

9
tools/vipsthumbnail.c
View File

@ -187,11 +187,14 @@ calculate_shrink( VipsImage *im )
/* Calculate the horizontal and vertical shrink we'd need to fit the
* image to the bounding box, and pick the biggest.
*
* In crop mode we aim to fill the bounding box, so we must use the
* In crop mode, we aim to fill the bounding box, so we must use the
* smaller axis.
*
* Add a small amount so when vips_resize() later rounds down, we
* don't round below target.
*/
double horizontal = (double) width / thumbnail_width;
double vertical = (double) height / thumbnail_height;
double horizontal = (double) width / (thumbnail_width + 0.1);
double vertical = (double) height / (thumbnail_height + 0.1);
if( crop_image ) {
if( horizontal < vertical )