W3C home > Mailing lists > Public > www-svg@w3.org > May 2010

Re: SVG Filters 2

From: Jasper van de Gronde <th.v.d.gronde@hccnet.nl>
Date: Mon, 31 May 2010 21:49:39 +0200
Message-ID: <4C0412D3.9000300@hccnet.nl>
To: Hans Schmucker <hansschmucker@gmail.com>
CC: www-svg@w3.org
Hans Schmucker wrote:
>>> Doing this would also mean getting rid of pre-multiplied colors (or at
>>> least the implicit conversions and the default setting of using
>>> pre-multiplied RGBA input), since these link RGB to A and make
>>> independent working impossible.
>> I'm not sure this is a good idea. Occasionally I have struggled with this,
>> but I think it might be better to handle this differently. If you have more
>> control over which channels are used you can ignore the alpha channel in
>> some filters for example. Also, if you can specify the kind of channels you
>> have you would be able to create images without an alpha channel.
> 
> Good point. But still, I wonder how else you can handle general
> "channels" and RGBA:
> A prerequisite of using channels is that each channel works
> independently: I'd be pretty
> confused if I found inside a spec "channels are handled independently,
> but RGB is
> always interpreted in relation to A". Of course, we could add an
> implicit conversion
> just for those filters that need it, but that would again mean
> limiting the use of that filter.

I don't think it would be so strange to just specify that if an A 
channel is present all other channels (or certain other channels) are in 
relation to it (for those purposes where we currently prescribe 
premultiplied colors).

(But I definitely can see your point about wanting to keep the logic 
simple.)
Received on Monday, 31 May 2010 19:50:10 GMT

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