small improvements to vips_resize() quality:
* turn down the anti-alias filter a little so we don't smudge out texture
* don't do the final sharpening pass if we skipped the anti-alias filter
* fix a >/>= mixup which meant we didn't sharpen for small resizes
sizealike() / formatalike() and bandsalike() used to just vips_copy() if
the image didn't need any changes ... this was fast, but left a
vips_copy_gen() in the pipeline, wasting a lot of space on the C stack
during recursion.
They now vanish completely if the image is already in the right format.
Since we call them before most image processing operations, and
often all three of them, this saves a lot of C stack, more than x2 even
in simple cases.
There might also be a measureable CPU saving if the operations are very
simple (eg. insert).
See:
http://stackoverflow.com/questions/33658795/difficulty-with-handling-very-large-image-using-vips
the tiff saver was writing all five-band images as CMYKA, even if they
were tagged as srgb ... it now follows the interpretation tag and will
write many alpha channels instead
see https://github.com/jcupitt/libvips/issues/348
thanks sadaqatullahn
we were just rint()ing masks going from float -> int, but this could
give bad results in some cases, with output images becoming darker
or lighter, as individual elemets moved up or down
now we adjust the output scale to try to keep the overall brightness
the same, if we can
see: https://github.com/jcupitt/libvips/issues/344
ruby gobject-introspection is quite fussy about needing a lot of const
declarations ... these changes help vips_image_matrix_from_array()
appear in Ruby
we used to issue a warning and return early, but this can leave garbage
in the *value pointer, I think
ruby gobject-introspection will walk object props during GC and can see
state inbetween init and build when not all objects have been given a
value ... we don't want these warnings
John Cupitt