On type & fonts
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Subpixel rendering vs hinting
10 January 2011
Too long for a tweet that it was supposed to become, here is a rather short note. In December I tweeted
but until now did not notice two replies which I want to address here.
A wrong term
You say 'subpixel hinting' when you actually mean 'subpixel rendering'. You are using the wrong term. It is like asking a colleague for a brush when you want him to hand over a piece of paper.
1. Subpixel rendering: Normal antialiasing, i.e. greyscaling, produces a shade of grey per pixel with help of all three colors that constitute the pixel.
[1] Subpixel rendering, in contrast, addresses each of a pixel's colors – each sub-pixel – independently. Doing so, it simulates a (quasi) three times higher resolution and provides a finer (sub)pixel grid on which outlines then are projected in a more precise way.
[2] The Microsoft articles to which I linked before –
this and
this – offer more detailed explanations and illustrations.
2. Hinting: This is special information
in fonts, helping rasterizers to position outlines properly on output devices' pixel grids. Rounding alone would result in oddly placed outlines and distorted letter forms. Hinting was needed most when type was rendered in pure black and white on low-resolution devices, both printers and screens. Tim Ahrens wrote a nice article about TrueType hinting for the
TypeKit blog.
In short, 'hinting' signifies something different than what you intend to signify. The right term for what you want to signify is 'rendering'.
Use of a wrong term, or wrong use of a term, in a single article is nothing to worry about since context shows what is meant. Unfortunately it happened in more articles than the above-mentioned two. Such wrong use of technical terms makes communication between type user and type foundry difficult especially when it comes to support and trouble-shooting.
An alternative term
@skoda Which term should I be using in regards to generating art assets that take subpixels into account? Subpixel positioning, or rendering?
It would be 'subpixel rendering' or, more precisely, something like 'simulation of subpixel rendering'. Admittedly, the latter is not particularly elegant.
[1] This is what Adobe Type Manager did, what 'Standard' smoothing does on Windows, and what Photoshop does.
[2] This is what 'ClearType' smoothing does on Windows, what OSX can do too now, and what you'd like Photoshop to do.
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