# Re: [css3-color] #rrggbbaa annotation

From: Alberto Lepe <dev@alepe.com>
Date: Tue, 6 Apr 2010 16:53:52 +0900
To: www-style list <www-style@w3.org>
```On Tue, Apr 6, 2010 at 4:30 PM, Patrick Garies <pgaries@fastmail.us> wrote:
> On 2010-04-06 1:37 AM, Brad Kemper wrote:
>>
>> This seems to assume that 0-255 is a natural way for an author to
>> think about color channels, but not about alpha channels. All four
>> channels are pretty much equivalent to me when I start thinking of a
>> particular value in one.
>
> I was relating to the most common scales used for opacity which is
> either 0%-100% or 0-1. Both scales are decimal-based.
>
> If an author could intuit things that way, you're right that it would make
> things easier and make the arguments that the calculation for opacity is
> both different and more effort moot.
>
> However, I that it's worth noting that you're still thinking in decimal
> (0-255) rather than hexadecimal, so it's still harder than the functional
> notation.
>
>> I figure the midway point is somewhere 127.5 on one scale, and
>> between 7E and 7F on the other. I never do the math; I either use a
>> color picker or I poke about with lighter or darker values in each
>> channel.
>
> The half-way point is the easy point. What if you want to go up 5%? It's not
> that hard when you sit there and think about it, but it's certainly harder
> than going from 0.5 to 0.55 as you would in the functional notation. If
> you're a stickler for precision, you can't get it with this notation either.
>
>> Thinking in terms of 0-255 is not much more natural to me
>> than thinking in terms of 0-16.
>
> You do make it sound easy. Unfortunately, that 0-16 is really 0-F where the
> first 0-F is a multiple of 15 and the second is a mapping to 0-16. This
> seems less natural to me.
>
>

Patrick, the problem here is that you are thinking that all the people
think of colors in a range of 0-100. You have expressed so many times
the math in order to convert from 0-100 to 0-255. You are taking as
granted that 0-100 is the "normal" way to do it. You are leaving aside
a big part of applications and languages that uses 0-255 ranges for
colors and for transparency. There is no way to express transparency
right now in a range of 0-255 in the actual CSS recommendation.
```
Received on Tuesday, 6 April 2010 07:54:25 UTC

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