vips_resize() uses to just use nearest when upsizing, following standard
practice in repro. This is often unfortunate for image processing, where
small nearest upsizes will produce obvious aliasing.
It now picks a VipsInterpolate which corresponds (roughly) to the
selected VipsKernel and uses that with affine for any upsizing.
vips_resize() used to do most of a downsize with vips_shrink() and the
final 200 - 300% with vips_reduce(). This was correct for lanczos2/3,
but not right for linear/cubic, which need more shrink and less
reduce to avoid aliasing.
This patch makes vips_resize() leave the final 100 - 200% to
vips_reduce() for linear/cubic, and leave everything to reduce for
nearest.
oops, it was missing
also, change the return type from void to VImage. This makes chaining
possible, eg.:
VImage memory = im.write( Viameg::new_memory() );
when you write to a non-partial image, you create a sink ... so
vips_image_write() only needs to ref the input when writing to partials
this change makes it much easier to (for example) combine many images in
bounded space, see for example:
https://gist.github.com/jcupitt/c516325ebef7601b5da610af5619c9b2
We were freeing pixel buffers on thread exit. This was convenient, but
meant that main thread buffers were not freed until program exit. As a
result, long-running programs which created main thread buffers would
slowly fill the operation cache with useless junk, forcing everything else out.
This change also frees pixel buffers on image close. This makes the
cache work much better in long-running programs, and can substantially
reduce memory use.
See https://github.com/jcupitt/libvips/issues/466
threads keep pixel buffers in thread-private storage, and free these
buffers on thread exit ... this means buffers created by the main thread will
only be freed on program exit!
if your program creates any main-thread buffers, these buffers will
eventually fill the operation cache and force everything else out,
making the cache useless
this patch explicitly frees main-thread pixel buffers on image close
when jpg compression is on, tiffsave now converts the input image for
jpg save ... previously, it would try to send a tiff-formatted image
(eg. perhaps with an alpha channel, or float data), which would fail
see https://github.com/jcupitt/libvips/issues/449
vips_unpremultiply() always outputs float. If you save the output of
vipsthumbnail to a format that supports float files, like tiff, it won't
ever get cast back to the source format.
Example:
$ vipsheader Opera-icon-high-res.png
Opera-icon-high-res.png: 3056x3325 uchar, 4 bands, srgb, pngload
$ vipsthumbnail Opera-icon-high-res.png -o x.tif
$ vipsheader x.tif
x.tif: 117x128 float, 4 bands, scrgb, tiffload
This change makes it note and restore BandFmt aropund pre/unpremultiply.
See https://github.com/jcupitt/libvips/issues/447
GM is still using the old page interface of subimage/subrange, IM has
deprecated that in favour of scene/number_scenes
we were accidentally just supporting the new IM system ... this change
adds support for GM as well, plus a configure test to pick one
see https://github.com/jcupitt/libvips/issues/423
jpeg write is more careful about removing exif tags that have been
removed from the image metadata
it failed previously if there were multiple Orientation tags
you can now put options like [scale=2] at the end of out_format ...
these are stripped before running the command, but use to load the
output image back into libvips again
John Cupitt