Roman / italic relationship throughout design space

[vikagrabowska]

I posted my observations on Opsz 5, roman / italic relation first https://github.com/clauseggers/Playfair/issues/45
Claus, I've seen that you replied today, that you are not sharing my point in this case.
However in the meantime I have been working on further observations about roman / italic relation throughout the whole design space, and in both Cyrillic and Latin scripts. I would like to share them with you, as perhaps they could bring a new, and a bit more comprehensive perspective on that matter.

The largest optical size opsz 1200 is showing the opposite tendency in relation roman / italic in comparison to opsz 5. Here Italic has more dense colour than roman. While it is an expected relation, I think optically it is too differentiated.
This is noticeable across the whole range of widths, but is especially prominent in narrower width, esp. the width 50.

This tendency is more subtle yet still resent in Latin, it is happening in the same progression, from more noticeable in narrow to less prominent in wides. It seems like more intense effect in Cyrillic is created by a higher frequency of stems / verticals.

It is happening in heavy weight wght 900 as well, just less noticeable than in weight 360.
I also have an additional note about zhe-cy, in heavy italics it seems pretty dense, especially in narrow width. It is the fault of a skeleton, this letter is often a noticeable spot in the overall colour, but I think decreasing the weight of strokes (and if needed, a slight narrowing of the curved c-like parts) could be helpful to calm it down in text.

Latin presents a similar relation between roman and italic as Cyrillic, but the effect of the differentiation is milder.

While looking at the widths in both roman and italics there is also a noticeable effect of text colour becoming lighter with decreasing width. This is present in both Latin and Cyrillic. This makes me wonder if in large optical size opsz 1200:
— wide masters can be spaced more tightly
— italics masters can be spaced looser than upright
— Cyrillic spacing can be loosened up slightly in comparison to Latin. I think this might be worth addressing in the glyphs with stems can receive slightly wider sidebearings, or just adding extra spacing to the glyph pe-cy which can be used as a key glyph for metrics of many Cyrillic glyphs in both upright and italics. Below is a duo script setting showing the density of Cyrillic.

Observing Latin and Cyrillic made me want to check opsz 5 again as well.

What strikes me there is that the issue of Wide upright being significantly wider from Wide Italic in wdth 150 doesn’t have such a strong presence in Latin as in Cyrillic.

I made a mixed scripts test and noticed that upright wide Cyrillic (opsz 5; wdth 150) seems wider than Latin. The first suspect is serifs which are much more frequent in Cyrillic, and rater closed apertures in glyphs like п, ш, щ, ц, и, н. Maybe if their serifs are slightly shorter and apertures are more open the colour would be easier to match with Latin and wouldn’t need editing the actual proportions of Cyrillic?

Below is the similar set of tests for the heavy wght 900 in opsz 5.

Cyrillic

Latin

Mixed scripts