WebP: expose the 'method' encoding parameter

[skal65535]

Hi,

looking at the WebP compression pameter (https://sharp.pixelplumbing.com/en/stable/api-output/#parameters_5), it seems that an important encoding parameter ('method') is lacking exposure.
See: https://developers.google.com/speed/webp/docs/api#advanced_encoding_api

'method' is used to specify the amount of efforts spent to further try and reduce the output size (both lossy and lossless).

While 'method' is the internal name, a better public name would be 'reduction_effort', i guess.

Thanks!
skal/

[lovell]

Bonjour Pascal, merci beaucoup for all your work on WebP.

This will need to be exposed in libvips first - I'll take a look - are there any other important WebP encoding parameters you believe are missing?

[skal65535]

Hi @lovell !

Oh, sorry i didn't know the lower layer was 'libvips'. I only looked around sharp code quickly, sorry.

I think 'method' is pretty much the main one missing, for everyday use.

Potentially, 'sharp_yuv' option, when doing RGB->YUV conversion, could be useful for avoiding some smearing of colorful edges (useful for comics, e.g.).
The option is also found in WebPConfig (see https://github.com/webmproject/libwebp/blob/master/src/webp/encode.h#L148)

Thanks again!
skal/

[lovell]

I've added this to libvips via libvips/libvips#1212 for inclusion in the forthcoming libvips v8.8.0, after which we can expose it in sharp.

[skal65535]

excellent! Thanks a lot @lovell .

[lovell]

sharp v0.23.0 / libvips v8.8.1 is now available.