Pike v8.1 release 6

Method Image.WebP.encode()


Method encode

string encode(Image.Image image, mapping(string:int|float|Image.Image)|void options)

Description

Encode an image using the WebP format.

The image to encode has to be at most 16384 pixels in any direction.

Commonly used options:

"alpha" : Image.Image

If present, the alpha channel for the image will be the green component of this image. Has to be the same size as the image

"preset" : int

Initialization for the encoding options. One of PRESET_DEFAULT, PRESET_PICTURE, PRESET_PHOTO PRESET_DRAWING, PRESET_ICON and PRESET_TEXT

"lossless" : bool

If set, do lossless encoding.

"quality" : float

Between 0 and 99. If quality is 100+, lossless encoding with quality 70 will be used.

Additionally these advanced options are also supported:

"image_hint" : int

One of HINT_DEFAULT, HINT_PICTURE, HINT_PHOTO and HINT_GRAPH. Only used in lossless mode

"target_size" : int

If non zero, sets the desired filesize, in bytes. Takes precedence over quality.

"target_PSNR" : int

if non-zero, specifies the minimal distortion to try to achieve. Takes precedence over target_size.

"segments" : int(1..4)

maximum number of segments to use.

"sns_strength" : int(0..100)

Spatial Noise Shaping. 0=off, 100=maximum.

"filter_strength" : int(0..100)

0=off

"filter_sharpness" : int(3bit)

0=off

"filter_type" : bool

For the type, 0=simple, 1=strong.

autofilter : bool

If true, automatically adjust the filter strengths

"alpha_compression" : bool

Select alpha channel encoding format. Currently supported are 0: No alpha and 1: WebP lossless

"alpha_filtering" : int(0..2)

Select alpha filtering method. 0: none, 1: fast, 2: best. Default if 1.

"alpha_quality" : int(0..100)

Select the base image quality for the alpha channel.

"pass" : int(1..10)

The number of entropy analysis passes. Defaults to 1.

"show_compressed" : bool 
"preprocessing" : bool

If true, do preprocessing (segment-smooth)

"partitions" : int(2bit)

log2(number of token partitions). Default is set to 0 for easier progressive decoding.

"partition_limit" : int(0..100)

quality degradation allowed to fit the 512k limit on prediction modes coding (0: no degradation, 100: maximum possible degradation).

"emulate_jpeg_size" : bool

If true, try to map the quality setting to generate similar sizes when compared to jpeg.

"thread_level" : int

The maximum number of extra threads to use. Defaults to 0

"low_memory" : bool

Decrease memory usage at the cost of encoding speed

Returns

Always returns the encoded image as a string or throws an error.