Can a toggle be added to the APCA tool to present values for serif fonts

[sdw32]

I would have thought that the relationship between size and readability for serif fonts would be considerably different to sans serif fonts. Serif fonts tend to be considerably thinner, but more shapely, which I believe increases their readability, above what one might expect from their size.

As such, I would have thought minimum size specifications (as a function of the luminance contrast) for serif fonts would need to be calibrated separately to sans-serif fonts.

The current guidance suggest there is a direct comparison as follows (from https://www.myndex.com/SAPC/

Many serif fonts should use values for the row above (e.g., Times, Georgia, Cambria, Courier), and especially should be compared in terms of x-height.

It would be interesting to see the evidence that supports this equivalence of readability. However, even if there is a simple equivalence in this way, I would think the tool would be much more useful if it would be possible to toggle whether it is showing values for serif or sans serif typefaces.

[Myndex]

@sdw32 Thank you for the comment.

The APCA tool's functionality is not a part of Silver/WCAG 3.0 — it is only a demonstrator of the APCA base algorithm.

For feature requests and bug reports related specifically to the APCA TOOL features and interface, please create an issue at the GitHub repo for the tool at https://github.com/Myndex/SAPC-APCA

Thank you,

Andy

Andrew Somers W3 AGWG Invited Expert Myndex Color Science Researcher Inventor APCA

[Myndex]

Hi @jspellman Just FYI, I had only closed it as it does not apply to APCA, only to a demonstrator tool.

My present undertanding is that there is and needs to be a separation between "tool" and the underlying guideline. Please let me know the correct boundaries here as it must not be clear to me.

Thank you

Andy

[alastc]

Hi @Myndex, we have a process to follow for issues raised, even if they are apparently off-topic. Only the TF facilitators or Chairs (or the issue raiser) should close issues.

In this particular case, there might be a question to answer in terms of the impact of serif vs non-serif fonts, even if it is just a matter of documenting that it doesn't matter (so the question doesn't come up again!)

[Myndex]

Hi @Myndex, we have a process to follow for issues raised, even if they are apparently off-topic. Only the TF facilitators or Chairs (or the issue raiser) should close issues.

Ah this makes sense, sorry for the misunderstanding.

The impact though is not serif vs sans-serif, but the comparison with any of many various font designs and font metrics, as we've discussed in the past there are no "useful" standards (PANOSE notwithstanding) in terms of readability. The BBC's accessibility department is presently conducting research, and in the wcag issue #665 you may remember we discussed some ideas here.

Ultimately, right now the technology does not exist. And this is a recognized issue without resolution for centuries.

But existing readability research including that of Legge indicates that there is no significant different given glyphs that are generally well designed, other metrics being equal.

In the case of Times vs Helvetica: the difference is not serif vs sans, but that the glyphs in Times have a much smaller x-height.

As I have stated previous, the bigger problem right now is that there is no standardization nor way to effectively set size by height, and tracking/leading relative therein ( letter spacing/line spacing). Readability research identifies x-height and tracking/leading as the critical metrics, more so than for serif/sans etc.

Thank you

Andy

[ChrisLoiselle]

@jspellman @Myndex has answered the question regarding fonts, separate from the tool question, for which he also answered. This is ready for survey.

[ChrisLoiselle]

DRAFT RESPONSE: We believe the question has been answered per Andy's response on Mar 5 regarding fonts. We also believe that he has answered the separate question around tools. I hope this answers your question, if it does not, please feel free to follow-up. Thank you, Chris

[sdw32]

Many thanks to all for following up on this discussion.

I think it would make sense to refine this particular thread to the guideline, rather than the APCA tool. I believe the "APCA CONTRAST LOOKUP TABLE" is part of the guideline, and the tool is essentially a dynamic way of interrogating this table that includes a live colour picker for the colour combinations. Please let me know if I have misunderstood this!

So, considering the lookup table, which intends to cover multiple typefaces, it is indeed a great shame that there is no guarantee of equivalence between one font-weight and another, or indeed font-size or line-height. Serif vs sans serif is another variable to throw in the mix, and I would expect font-weight 400 serif fonts are typically thinner than font-weight 400 sans serifs.

In order to resolve this in a pragmatic manner, I think we need a small handful of common typefaces where the APCA CONTRAST LOOKUP TABLE has been validated. I would imagine we might end up with two different lookup tables, one for a set of serif reference fonts, and a different one for a set of sans serif reference fonts (given the differences in font-weights). Although of course, the more reference typefaces the better! if it turns out that the table is genuinely the same for both serif and sans serif then that's simpler, although I'd be keen to see the evidence that this remains true across the different font-weights.

Then, for any other typeface, I think the guideline needs to include a way of mathematically calibrating the values of a chosen typeface to the values of the most similar reference typeface (or confirming that they can be used directly without modification). I would imagine something along the lines of:

• the x-height of the chosen typeface should be greater than or equal to the x-height of the reference typeface AND
• the line-height of the chosen typeface should be greater than or equal to the line-height of the reference typeface AND
• the strokes that make up the letters should be at least as wide as the letters of reference typeface.

For reference, on this topic, the current APCA tool includes the following text (although I think this text and the accompanying lookup table should be part of the guideline rather than part of the APCA tool)

Many serif fonts should use values for the row above (e.g., Times, Georgia, Cambria, Courier), and especially should be compared in terms of x-height. Decorative, unusual, and very thin fonts should be avoided for columns of body text. Due to the vast variety of font designs, designers should visually compare an unusual font to a standard font such as Helvetica, using the size and weight of Helvetica that most closesly matches the appearance of the tested font as a guide.

So, what I'm proposing is essentially a more specific elaboration of what it means to 'visually compare' one font specification against another, and to have: at least one reference sans serif font that can be used to compare any other sans serif font against AND at least one reference serif font that can be used to compare other serif fonts against

I will look forward to further discussion on this topic.