[Standards] XEP-0392 angle generation

Jonas Wielicki jonas at wielicki.name
Wed Nov 29 10:37:19 UTC 2017

Hi Marcel and others,

First of all, thank you for your valuable feedback. I have incorporated
it into an update of XEP-0392 which I’ll publish soon.

On 23.11.2017 18:22, Marcel Waldvogel wrote:
>>> * 5.5 Adapting the Color for specific Background Colors I presume
>>> this "inverse alpha" calculation should be applied always, even on
>>> white backgrounds? 
>> Maybe™. We need deployment experience with that (I only played around with it 
>> on some uniformly colored backgrounds for testing, and there the effect was 
>> quite useful). Another way I am thinking of is to fully saturize the 
>> background color for the "inverse alpha" calculation and separate the color 
>> (hue) from a to-be-specified brightness adaption.
>>> Otherwise, there is a discontinuity. It would be good to explain the
>>> rationale behind this part. 
>> Can you specify what is unclear here?
> With discontinuity, I meant that there will be a different color chosen
> for those that use the color before 5.5 and after 5.5. So it would be
> good to state to always apply 5.5 (or to never apply it or …).

Yes, 5.5 MAY be applied to grayscale backgrounds, but does not have to
be  applied. It doesn’t change the hue and it is up to the client
(developer) to decide whether adaption is necessary. It does not harm
either way.

For coloured backgrounds, applying 5.5 is RECOMMENDED because it
provides contrast even in extreme situations. Alternatively, a border or
similar mechanism can be used.

I’ll add wording with respect to that to the next update.

kind regards,

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