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Re: [CSS4 color][CSS4 transition] color pre-multiplied vs non pre-multiplied was (Re: [CSSWG] Minutes TPAC Tue 2012-10-30 AM I: Abstract Directions, Transforms, Transitions)

From: Rik Cabanier <cabanier@gmail.com>
Date: Sun, 3 Mar 2013 22:34:58 -0800
Message-ID: <CAGN7qDCqoQHRL6v3Uehj37m8zCEgt1EvcOacJsZ5vENCvkCnJQ@mail.gmail.com>
To: Brad Kemper <brad.kemper@gmail.com>
Cc: "Tab Atkins Jr." <jackalmage@gmail.com>, Liam Quin <liam@w3.org>, "www-style@w3.org" <www-style@w3.org>
On Sun, Mar 3, 2013 at 9:12 PM, Brad Kemper <brad.kemper@gmail.com> wrote:

> I don't know how red got in there, if i am trying to create a green to
> transparent gradient in PhotoShop. I think I would either change all that
> red to green, or make sure there was green to green in the gradient.
>

You have a green layer and are just changing the alpha channel
So green + 100% opacity to green + 0% opacity

>
> Anyway, I still don't get your point. How is that like the gradients that
> would go from green to transparent black, or from red to transparent black,
> the way Safari does it? I must be missing something.
>

They don't go to transparent in photoshop. They go from a color with
opacity to another color with opacity.
There's no premultiplication like css has so it will be hard for authors to
reproduce mockups that we designed in other applications such as PhotoShop.


>
> On Mar 2, 2013, at 8:56 AM, Rik Cabanier <cabanier@gmail.com> wrote:
>
>
>
> On Sat, Mar 2, 2013 at 1:11 AM, Brad Kemper <brad.kemper@gmail.com> wrote:
>
>> The sliders would be for, say, a gradient fill on a layer effect, right,
>> or for creating a new gradient fill on the palette and then dragging the
>> gradient tool across a transparent background?
>>
>
> It's for the gradient fill in the palette.
>
>
>> Yes, that's another way to do it, instead of what I described (a little
>> more work, if you ask me, since black-to-white is already a preset, and
>> creating a alpha channel for the whole image takes but a single click). And
>> yes, the color slider would be green to green, and the opacity slider would
>> be 100% to 0%. I wouldn't set it as green to black.
>>
>
> That's completely different though. The color of your layer is red and
> you're just changing it's opacity. (The gradient effect comes only from the
> opacity. Adobe applications split color and opacity to avoid confusion)
> It would again be like going from rgba(0,255,0,1) to rgba(0,255,0,0)
>
>
>>
>> On Feb 28, 2013, at 1:01 PM, Rik Cabanier <cabanier@gmail.com> wrote:
>>
>> Photoshop has 2 sliders. One to control the color and the other to
>> control the opacity.
>> The opacity slider has no color. What are the colors in the other slider?
>> Is it all green?
>>
>> On Thu, Feb 28, 2013 at 12:49 AM, Brad Kemper <brad.kemper@gmail.com>wrote:
>>
>>> On Feb 27, 2013, at 8:25 AM, Rik Cabanier <cabanier@gmail.com> wrote:
>>>
>>> Special casing 'transparent' fixes that in an intuitive way. It's more
>>> confusing to authors that CSS gradients are different from any other type
>>> of gradient.
>>> Good luck trying to match that CSS gradient with the one in PhotoShop!
>>>
>>>>
>>> I'm pretty certain I'm missing your meaning. If I create a solid to
>>> transparent gradient in PhotoShop, I fill the shape (let's say a rectangle)
>>> with a solid color (let's say, green) in the rgb channel, and then put a
>>> black to white gradient into the alpha channel. I don't create a green to
>>> black gradient in the rgb channel the way safari does.
>>>
>>
>>
>
Received on Monday, 4 March 2013 06:35:56 GMT

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