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From: David MacDonald <befree@magma.ca>
Date: Tue, 2 Nov 2004 21:37:47 -0500
Message-Id: <200411030237.iA32blNk008853@mail1.magma.ca>
To: <w3c-wai-gl@w3.org>
Cc: <wendy@w3.org>, "'Ben Caldwell \(E-mail\)'" <bcaldwell@wisc.edu>
I had an action item to clear the open issues bugs for Guideline 1.4.

 

My recommendations are summarized directly below with more detail further
below I will be proposing a couple of wording changes to the guidelines
tomorrow:

 

344 - leave open, need a contrast alga rhythm
454 - leave open, need a contrast alga rhythm
489 - leave open, need a contrast alga rhythm
592 - leave open, need a contrast alga rhythm
996 - leave open until we have an alga rhythm, it suggests an extensive
study of users to determine acceptable contrast
1006 - close, the wording is fixed and is waiting for a concrete contrast
scale
1025 - discuss with group, perhaps add a sentence discouraging the use of
absolute text sizes.
1038 - close, example is clear now
1039 - close, I've made sufficient audio contrast examples I think (for
general techniques)
1181 - close, I've done sufficient research on audio contrast 
1187 - move to 1.3 issues, it was put in 1.4 by mistake
1188 - move to 1.3 issues, it was put in 1.4 by mistake
1208 - close,  issue was fixed

1209 - close, issue was fixed 
1235 - close, issue was fixed  

 

 

More detail

 

 

344. Algorithm for testing foreground/background contrast , (Issue 454, 489,
592 are related.)

 

I think these bugs should remain open until we decide on an alga rhythm or
have a tool for measuring contrast. So far I know of no tool to measure
contrast. If the ala rhythm in Chris Ridpath's document is good, then it
would be reasonably do-able to make a tool. 

________________

Color brightness is determined by the following formula:
((Red value X 299) + (Green value X 587) + (Blue value X 114)) / 1000
Note: This algorithm is taken from a formula for converting RGB values to
YIQ values. This brightness value gives a perceived brightness for a color.

Color difference is determined by the following formula:


(maximum (Red value 1, Red value 2) - minimum (Red value 1, Red value 2)) +
(maximum (Green value 1, Green value 2) - minimum (Green value 1, Green
value 2)) + (maximum (Blue value 1, Blue value 2) - minimum (Blue value 1,
Blue value 2))

The rage for color brightness difference is 125. The range for color
difference is 500. (Can't close)

>From http://www.w3.org/TR/AERT 

 

#592 Guideline 1.5, recommend adding "or other background sounds" to the end
of this sentence. This applies to more 
than just "music." (Lorreta) 

 

(We can close this)

 

#996 suggests someone take a large sample of users and do a study to find a
level of contrast that works. Mattew Wickline lays out the basis of a study.
He doesn't think we will get good numbers without a study. 

 

(Can't close)

 

#1006. Level 3 SCDescription:

Ian Jacobs writes: 1.4, Level 3 SC: - 

"Text is not presented over a background image or pattern, or if a
background image or pattern is present, the text is easily readable when the
content is viewed in grayscale." Even written that way, "easily readable"
will be highly subjective. 

 

(We can close this, the guideline now has a concrete number - sort of -
we're still looking for the alga rhythm but the wording no longer
subjective)

 

1025. Text size 

Rik writes: I did not find anything about the size of text (perhaps I've
missed it)- text should always be enlargeable (everyone can bebefit form
this). So absolute measurements for fonts should not be used.

 

( I would like to discuss this with the group. This is covered in the
techniques docs but I think it might to be safe to include a line in the
guideline about not using absolute sizes of text.)

 

1037

"Alternatively provide a presentation without the background, such as the
frequently found "print" option."

 

David's Recommendation: I think we can close this because the "no
background" suggestion is now covered at Level 3

 

#1038. Explicitly say "no letters are light on dark" in the example

Description: In Example 1, why leave implicit that "no letters are light on
dark?"

David's Recommendation: I think we can close this, it is clear in the
example I think

 

#1039. 20 dB difference will be difficult to verify 

Description: Note: A 20 db difference in sound level. I expect that such
background sound that meets this requirement will be 

approximately four times (4x) quieter than the foreground audio content -
will be hard to verify--particularly when there are competing sounds.

 

David's Recommendation: I think we can close this. I think the examples I
made that will go in the general techniques will give authors a feel for
what 20db contrast sounds like.)

 

#1081. references for 20 db value?

Description:

Also, who came up with the 20 dB (or 4 X louder) foreground/background audio
figure? Are there any data to back this up as being sufficient?

 

David's Recommendation: I think we can close this. I've researched this
thoroughly and the minimum of 20dbs is generally considered a sufficient
minimum among experts in this field. I will recommend wording that stresses
20db's as a *minimum*.)

See: http://lists.w3.org/Archives/Public/w3c-wai-gl/2004OctDec/0246.html 

http://lists.w3.org/Archives/Public/w3c-wai-gl/2004OctDec/0236.html 

 

#1087. Difference between 2 success criteria for color use is confusing. 

Description:

Comment 1, (Andi Snow-Weaver): Guideline 1.3

 

David's Recommendation: (this guideline is mistakenly included in 1.4 bugs
when it should be in 1.3)

 

#1088. Add an example to Guideline 1.3, SC2.Description:

Comment 1, (Andi Snow-Weaver): Guideline 1.3

 

David's Recommendation: (this guideline is mistakenly included in 1.4 bugs
when it should be in 1.3)

 

#1208. are success criteria levels backwards?

Description:

Comment 1, 1. Level 3 Success Criteria 1: This Success Criteria says it only
covers 

default backgrounds while Level 2 Success Criteria1 covers backgrounds in 

general. Level 3 Success Criteria 1's coverage is narrower than Level 2 

Success Criteria 3's. If this is the case, these criteria should be swapped.

 

David's Recommendation: I think we can close this because Level 3 SC 1 no
longer says default. It says *any* 

 

#1209.Should 1.5 be a level 3 guideline?

Description:

Comment 1, (Loretta Guarino Reid): Guideline 1.5

1. It is odd having an Level 2 guideline with no Level 2 Success Criteria. 

What is the reasoning for not make this a Level 3 guideline or change the 

Level 3 Success Criteria to Level 2 Success Criteria?

 

David's Recommendation: I think we can close this because its been addressed

 

#1235. Issue Summary for guideline 1.4 (visual-audio-contrast)

Description:

Comment 1, (Ben Caldwell): Action items from October 2004 face to face to
complete issue summaries for

various categories of open issues related to WCAG 2.0

David's Recommendation: I think we can close this because its been addressed

 

 

 

 

 

 

------------------------------------------

Access empowers people...
         .Barriers disable them.

 

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Received on Wednesday, 3 November 2004 02:37:56 GMT

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