Method

VipsImagereduce

Declaration [src]

int
vips_reduce (
  VipsImage* in,
  VipsImage** out,
  double hshrink,
  double vshrink,
  ...
)

Description [src]

Optional arguments:

kernel: VipsKernel to use to interpolate (default: lanczos3)
gap: reducing gap to use (default: 0.0)

Reduce in by a pair of factors with a pair of 1D kernels. This will not work well for shrink factors greater than three.

Set gap to speed up reducing by having vips_shrink() to shrink with a box filter first. The bigger gap, the closer the result to the fair resampling. The smaller gap, the faster resizing. The default value is 0.0 (no optimization).

This is a very low-level operation: see vips_resize() for a more convenient way to resize images.

This operation does not change xres or yres. The image resolution needs to be updated by the application.

See also: vips_shrink(), vips_resize(), vips_affine().

This method is not directly available to language bindings.

Parameters

`out`	`VipsImage`
	Output image.
	The argument will be set by the function.
	The instance takes ownership of the data, and is responsible for freeing it.
`hshrink`	`double`
	Horizontal shrink.
`vshrink`	`double`
	Vertical shrink.
`...`
	`NULL`-terminated list of optional named arguments.

Return value

Returns:	`int`
	0 on success, -1 on error.