the extra check on bandfmt in sizeof() in 8.3.2 was causing some performance
problems ... move the check to file read, so we only do it once
per image, not once per pixel or scanline
thanks Lovell!
- transparency was broken if image had no extension block
- load image to memory, test for transparency and mono/colour, write 1,
2, 3, or 4 band image to output, depending on what we found
getting --fail on jpegload working means tilecache must terminate on tile
calc error
make openslideload not report tile calc errors, it might need a --fail
option too
see https://github.com/jcupitt/libvips/issues/474
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
