Re: Grayscale, lacuna value, and optional argument

For what it's worth, this seems to be how -webkit-filter is implemented.
In other words, -webkit-filter: grayscale() applies 100% grayscale filter
(in Chrome anyway, haven't tested Safari).

For implementers of the standard property, neither Edge nor Firefox
currently support the function without a parameter, so changing the lacuna
value would not break anything that isn't already broken.

I also agree that it is more useful/logical to have the default function be
complete grayscale.


On 1 February 2016 at 15:02, Chris Lilley <> wrote:

> Hello,
> The ED of filters says that the lacuna value for the grayscale filter is
> zero.
> However:
>  - the syntax does not seem to allow the argument to be omitted so how
>    can the lacuna value be used
>  - if it did, then 0 is an odd value
> 0 means no change. Thus seems unintuitive. I would expect grayscale()
> to be equivalent to grayscale(100%) which is likely what authors would
> expect and would be convenient for the most common use case "make this
> grayscale".
> Suggested fix:
>  - change the grayscale filter syntax to make the argument optional
>  - change the lacuna value to 1
> Btw I added some tests for grayscale since there was only one (100%)
> so I added 1, 0, 0% and 300% as well.
> --
> Best regards,
>  Chris  Lilley
>  Technical Director, W3C Interaction Domain

Received on Monday, 1 February 2016 22:25:41 UTC