intvips_reducev(VipsImage*in,VipsImage**out,doublevshrink,...)

Reducein vertically by a float factor.

The pixels inout areinterpolated with a 1D mask generated bykernel.

Setgap to speed up reducing by havingvips_shrinkv() to shrinkwith a box filter first. The biggergap, the closer the resultto the fair resampling. The smallergap, the faster resizing.The default value is 0.0 (no optimization).

This is a very low-level operation: seevips_resize() for a moreconvenient way to resize images.

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

This method is not directly available to language bindings.

out

Type: VipsImage

Output image.

The argument will be set by the function.

The caller of the method takes ownership of the returned data, and is responsible for freeing it.

vshrink

Type: double

Vertical reduce.

...

Type: 

NULL-terminated list of optional named arguments.