Method

VipsImagepngsave

Declaration [src] 

int
vips_pngsave (
  VipsImage* in,
  const char* filename,
  ...
)

Description [src]

Optional arguments:

  • compression: %gint, compression level
  • interlace: %gboolean, interlace image
  • filter: VipsForeignPngFilter row filter flag(s)
  • palette: %gboolean, enable quantisation to 8bpp palette
  • Q: %gint, quality for 8bpp quantisation
  • dither: %gdouble, amount of dithering for 8bpp quantization
  • bitdepth: %gint, set write bit depth to 1, 2, 4, 8 or 16
  • effort: %gint, quantisation CPU effort

Write a VIPS image to a file as PNG.

compression means compress with this much effort (0 - 9). Default 6.

Set interlace to TRUE to interlace the image with ADAM7 interlacing. Beware than an interlaced PNG can be up to 7 times slower to write than a non-interlaced image.

Use filter to specify one or more filters, defaults to none, see VipsForeignPngFilter.

The image is automatically converted to RGB, RGBA, Monochrome or Mono + alpha before saving. Images with more than one byte per band element are saved as 16-bit PNG, others are saved as 8-bit PNG.

Set palette to TRUE to enable palette mode for RGB or RGBA images. A palette will be computed with enough space for bitdepth (1, 2, 4 or 8) bits. Use Q to set the optimisation effort, dither to set the degree of Floyd-Steinberg dithering and effort to control the CPU effort (1 is the fastest, 10 is the slowest, 7 is the default). This feature requires libvips to be compiled with libimagequant.

The default bitdepth is either 8 or 16 depending on the interpretation. You can also set bitdepth for mono and mono + alpha images, and the image will be quantized.

XMP metadata is written to the XMP chunk. PNG comments are written to separate text chunks.

See also: vips_image_new_from_file().

This method is not directly available to language bindings.

Parameters

filename

Type: const char*

File to write to.

The data is owned by the caller of the method.
The value is a NUL terminated UTF-8 string.
...

Type: 

NULL-terminated list of optional named arguments.

Return value

Type: int

0 on success, -1 on error.