# Re: [css3-color] #rrggbbaa annotation

From: Patrick Garies <pgaries@fastmail.us>
Date: Tue, 06 Apr 2010 02:30:37 -0500
Message-ID: <4BBAE31D.7000305@fastmail.us>
CC: Biju <bijumaillist@gmail.com>, www-style list <www-style@w3.org>
```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.
```
Received on Tuesday, 6 April 2010 07:31:12 UTC

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