Typegenius "Sharpness"

[RobertJSawyer]

Kobo's "Typegenius" feature (accessible if you select "Advanced" next to a font name) lets you adjust "Weight" and "Sharpness."

I get what "Weight" does -- it makes the characters bolder -- and can clearly see the difference as I adjust the slider.

But I don't understand what "Sharpness" does. I can't see a visible difference on my Kobo Glo (although I have aging eyes, so that shouldn't be taken to mean that there is no difference). What, precisely, does Sharpness adjust? What does it change on a per-pixel basis?

Thanks!

[ectoplasm]

I think it refers to anti-aliasing, or the addition of grey pixels surrounding the sharp edges of the font. Sharper would mean less anti-aliasing. The effect could be invisible if the DPI is high enough or if you hold the device far enough away, or if your eyesight is not sharp enough to see pixels.

[DNSB]

Originally Posted by RobertJSawyer

Kobo's "Typegenius" feature (accessible if you select "Advanced" next to a font name) lets you adjust "Weight" and "Sharpness."

I get what "Weight" does -- it makes the characters bolder -- and can clearly see the difference as I adjust the slider.

But I don't understand what "Sharpness" does. I can't see a visible difference on my Kobo Glo (although I have aging eyes, so that shouldn't be taken to mean that there is no difference). What, precisely, does Sharpness adjust? What does it change on a per-pixel basis?

I haven't really looked at it but the two techniques popular for increasing the perceived sharpness of a font are subpixel rendering which is more commonly found on colour displays (LCD, OLED) and is used by Microsoft's ClearType, Quartz, Adobe's CoolType, etc -- basically, you use the 3 colours to effectively triple the resolution though if you look closely enough, you can see colour fringing. The other option is pixel anti-aliasing which can be used with hinting to improve the appearance. From what I've seen playing with TypeGenius, is that Kobo's fonts that support TypeGenius without Metazoa's patch have the hinting information.

You can check Wikipedia for more on subpixel rendering and other anti-aliasing techniques. One quick link is http://en.wikipedia.org/wiki/Font_rasterization.

Regards,
David

[tls]

Originally Posted by RobertJSawyer

Kobo's "Typegenius" feature (accessible if you select "Advanced" next to a font name) lets you adjust "Weight" and "Sharpness."

I get what "Weight" does -- it makes the characters bolder -- and can clearly see the difference as I adjust the slider.

But I don't understand what "Sharpness" does. I can't see a visible difference on my Kobo Glo (although I have aging eyes, so that shouldn't be taken to mean that there is no difference). What, precisely, does Sharpness adjust? What does it change on a per-pixel basis?

Thanks!

If you have the Sharpness slider at the minimum level, you should see the characters have a grey halo and look almost blurry.

At the maximum level, that halo is gone. Edges will be sharp black/white.

[GeoffR]

So is it correct that it is faster to render fonts with higher sharpness? If so, and if I can't tell the difference between maximum and minimum sharpness, then I may as well just set it to maximum.

[FJames]

The amount of sharpness effect you'll see depends on the font you're using.

It's based on how the human eye perceives sharpness. When something looks blurry or out-of-focus to you, it's because the lines and edges are fuzzy, spread out in space and blending into each other. When something looks sharp, it's because there's high contrast at the lines and edges, changing quickly from dark to light (or vice-versa) instead of blending gradually. So to make something appear artificially "sharper" to your eyes, they simply increase the contrast of lines and edges, often exaggerating them to the point where there's a bright line on one side of the edge and a dark line on the other side. On the eInk screen it's a little bit more limited. All they can do is reduce or remove the grey blending pixels used for anti-aliasing the font.

[slantybard]

I commented on the sharpness in another post here.

[jackastor]

Originally Posted by RobertJSawyer

Kobo's "Typegenius" feature (accessible if you select "Advanced" next to a font name) lets you adjust "Weight" and "Sharpness."

I get what "Weight" does -- it makes the characters bolder -- and can clearly see the difference as I adjust the slider.

But I don't understand what "Sharpness" does. I can't see a visible difference on my Kobo Glo (although I have aging eyes, so that shouldn't be taken to mean that there is no difference). What, precisely, does Sharpness adjust? What does it change on a per-pixel basis?

Thanks!

I was just playing around with the settings on My Aura HD and notice that the text seems to shift a bit when playing with the sharpness.. So it looks to me that the text is smoothed out on the edges(?) making it appear to be more crisp. Then again I could be entirely wrong as I cant seem to find any resources on the net that explain it at all.

regards

Jack

[RobertJSawyer]

Thank you, everybody!