Re: Graphics contrast

Alastair,

I think you and I are thinking the same way.  The reason I'm not
comfortable just saying "adjacent elements" is...I think it will be
problematic to objectively measure.  Let's imagine a trashcan icon that is
being used as an interactive element. Here is a simple example from my
gmail account: [image: Inline image 1]
In this case, the primary color of the trashcan is dark grey (#6E6E6E) and
the primary color of the background is light grey (#F4F4F4).  Ignoring the
anti-aliasing bits around the end of the trashcan...I grab a pixel of the
dark grey to compare against a pixel of the light grey....and smile,
because it is 4.6 to 1.

BUT...what if the trashcan was rainbow striped diagonally, the lid was
light purple, the background color was the same light grey  (#F4F4F4) as
the previous example.

[image: Inline image 4]

For testing purposes...let's just focus on the lid...you would look at the
light purple lid, in your mind, draw a "need to test the background color"
3px perimeter around the edge of the lid.  Your brain then says...oh, that
is just one color in that 3px perimeter around the edge of the lid...so now
I'll compare the light purple: #CBCBFE to the light grey #F4F4F4...see it
is only 1.4 to 1, and say, that lid fails.

But if I had to do this with the trash can body...I would have to compare
each stripe of the trashcan against the 3 px surrounding area just outside
the edge of that color of the trashcan.

So...there is NO requirement for borders on anything.  BUT...for testing
purposes...we are going to look at the immediate 3 pixels perimeter.

Does that make sense?
G

P.S.  Yes, this is a unicorn's trash can :)

glenda sims    |   team a11y lead   |    deque.com    |    512.963.3773


*web for everyone. web on everything.* -  w3 goals

On Thu, Nov 10, 2016 at 5:03 PM, Alastair Campbell <acampbell@nomensa.com>
wrote:

> Hi Everyone,
>
> I was reading through the minutes, and considering the term "immediate
> surrounding background" for both contrast SCs.
>
> I think what we're actually trying to say is: "adjacent elements", and in
> the definition of that include the background as the obvious adjacent
> element.
>
> I.e. it doesn't matter if it is a background or another part of the same
> graphic, it is what is next to it that counts.
>
> That means we aren't asking for borders specifically (which seems
> implied), there are several techniques that can apply, such as breaking up
> a slices of pie chart with gaps in between, or a border, or just having
> contrasting colours.
>
> Therefore the graphics contrast SC would start:
> "The visual presentation of important information in graphical elements
> has a contrast ratio of at least 4.5:1 against the adjacent elements,
> except for the following:"
>
> Perhaps in the Interactive Element Contrast SC the term background is more
> applicable because we aren't expecting them to be next to the elements
> (apart from interactive graphics?)
>
> -Alastair
>