Style: M appears stylistically different to rest of Latin alphabet

[Johannes Albrecht]

Rendered in 75pt Regular

Sample Glyphs:

NMK

Description:

Capital M looks like it was from a completely different font.
The vertical lines should be a little more consistent - like in N and K.
The half-bent-half-straight style looks like one forgot to design the remaining part.

UA String:

Mozilla/5.0 (X11; U; Linux i686; en-US) AppleWebKit/534.6 (KHTML, like Gecko) Chrome/7.0.503.1 Safari/534.6

[David Marshall (dave-daltonmaag)]

The attached image is scaled, with pixels interpolated, so is not an
accurate depiction of the glyph or its rasterization. The open shape of
the M is an intentional design feature. If you find any specific issues
with it, please resubmit an image at native resolution, not scaled.

Dave

[Johannes Albrecht (sprechsucht)]

On a closer view it does'nt seem to be just a M-issue.
The bigger the size, the better it looks.

But while switching through the sizes the appearence/geometry seems to change.
I add a screenshot of NMK at 36pt and 37 pt to show this.

[Bruno Maag (bruno-daltonmaag)]

The Ubuntu font family can be classified as a humanist sans. It is therefore quite legitimate to have a splayed 'M' meaning that the outside stems are not dead vertical. In this particular instance, as these stems are deemed 'diagonal' we build in a curve, as have all the diagonals in the font family. This is an intentional design feature and if you observe K V W etc you'll find the same.

Diagonals are notoriously difficult to render on screen, and if they are slightly curved even more so. The inside diagonals will vary slightly depending on the rasterising method, and whether the hints are fully recognised. As David Marshall mentions in another thread, we have no control over the display on screen if the autohinter takes over.

[Paul Sladen (sladen)]

Johannes: the reason that the Ubuntu Font Family appears sharp on your screen is because it is "Hinted", this means that a small (manually written) computer program in the font *flexes* the geometry slightly to keep everything aligned to the pixel grid of the screen. The "step" that you are seeing is the increase by one to the next whole pixel width.

  http://en.wikipedia.org/wiki/Font_hinting

The vertical stems here are approximately 4.5 pixels wide, so to keep everything sharp you either have to round down to 4 pixels, or up to 5 pixels. At 48 pixels-per-em the stems are rounded down to 4 pixels wide, and at 49 pixels-per-em they are rounded up to 5 pixels. You should see similar transitions from at roughly-evenly-spaced intervals through out.

Does this make sense now? (It is highly intentional and a great deal of time to implement).

[Paul Sladen (sladen)]

(As a point of reference, in this screenshot we have the pixels-per-em readout from Deja Sans appearing to the left, which shows that the manual hint tables are in use and not the autohinter).

[Johannes Albrecht (sprechsucht)]

Paul: Thanks for all the information.
Is there a way to avoid those "steps" of the width-thickness-relations?
The steps seem a bit larger than in other fonts.

[Matthew Paul Thomas (mpt)]

This magnified screenshot shows first NMK firstly with manual hinting, and secondly with subpixel autohinting.

A slight diagonal curve, like here in the M, is an awkward choice for a UI font. As Bruno alluded to above, it's pretty much the worst shape for rendering at low resolution -- which is why, for example, Optima, Eras, and Souvenir are quite popular typefaces in print, but seldom seen in Web or UI design. <http://www.myfonts.com/search/optima+eras+souvenir/fonts/>

Hinting adjusts the width of the M at each size, so that, for maximum sharpness, both stems finish exactly on a pixel boundary. With most fonts we don't notice this width adjustment, because -- at the resolutions we're looking at -- the stems of an M are exactly vertical regardless. But in the Ubuntu font they're slightly diagonal, so when the width of the M changes, the angle of the stems changes too. At worst, in some sizes, the curve makes them look almost as if they're straight at the bottom and bent at the top.

Fortunately for this case, the Ubuntu UI defaults to using autohinting instead. The result is characters that are a bit blurrier, but more faithful to the shape -- in this case, keeping the angle of the curve more consistent between sizes. And with subpixel rendering the horizontal resolution is effectively tripled, allowing even greater consistency of angle.

So, unless there's a rather substantial change to the underlying design, I don't think anything can be fixed here.