- From: David MacDonald <befree@magma.ca>
- Date: Tue, 2 Nov 2004 21:37:47 -0500
- To: <w3c-wai-gl@w3.org>
- Cc: <wendy@w3.org>, "'Ben Caldwell \(E-mail\)'" <bcaldwell@wisc.edu>
- Message-Id: <200411030237.iA32blNk008853@mail1.magma.ca>
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. <http://www.eramp.com> www.eramp.com
Received on Wednesday, 3 November 2004 02:37:56 UTC