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Merged
merged 2 commits into from
Oct 14, 2022
Merged

spngsave: ensure quantisation occurs last #3073

merged 2 commits into from
Oct 14, 2022

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kleisauke
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i.e. after setting the metadata and phyiscal pixel dimensions, since quantisation will overwrite the image.

Before:

$ vips copy fruit-g236fa3733_1920.png x.png[palette]
$ vipsheader -f xres x.png
1
$ vipsheader -f icc-profile-data x.png
vipsheader: vips_image_get: field "icc-profile-data" not found

After:

$ vips copy fruit-g236fa3733_1920.png x.png[palette]
$ vipsheader -f xres x.png
2.835
$ vipsheader -f icc-profile-data x.png
<base64-encoded binary data>

Targets the 8.13 branch as this is a bug fix.

Originally reported at lovell/sharp#3392.

@kleisauke
spngsave: ensure quantisation occurs last
a403511 
i.e. after setting the metadata and phyiscal pixel dimensions,
since quantisation will overwrite the image.
@kleisauke kleisauke mentioned this pull request Sep 30, 2022
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@kleisauke
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Oh, perhaps we need to move this:

libvips/libvips/foreign/spngsave.c

Lines 380 to 389 in a403511

/* Low-bitdepth write needs an extra buffer for packing pixels.
*/
if( spng->bitdepth < 8 ) {
spng->sizeof_line = 1 + VIPS_IMAGE_SIZEOF_LINE( in ) /
(8 / spng->bitdepth);
if( !(spng->line =
vips_malloc( NULL, VIPS_IMAGE_SIZEOF_LINE( in ) )) )
return( -1 );
}

After the quantisation?

@kleisauke
spngsave: avoid over-allocation of temporary buffer
2a90aec 
For low-bitdepth write and palette-based output.
@kleisauke
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... 2a90aec, but that makes the overall diff a bit harder to review. PR is best viewed by commit.

@jcupitt jcupitt merged commit f38acde into libvips:8.13 Oct 14, 2022
@kleisauke kleisauke deleted the 8.13-spngsave-quantisation-last branch October 14, 2022 18:47
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2 participants
@kleisauke @jcupitt