Pixel Art Tutorial: Terms to Know

Terms to know

Anti-aliasing (AA):

[In addition to the information found in this section, check out this image by Ptoing.]

Anti-aliasing is the method of making jagged edges look smooth. You may be familiar with anti-aliasing already, because a lot of programs and tools do this automatically. When we’re talking about pixel art, however, anti-aliasing means manual anti-aliasing. Manual AA means smoothing the jagged areas by hand-placing pixels of a different color to ease the transition. Here’s an example:


               without AA                                     with AA added

There are several pitfalls often encountered when applying anti-aliasing, which are discussed in the “Things to avoid” section.

Dithering:

Dithering consists of different patterns of pixels. It’s typically used to ease the transition between two colors, without adding any new colors to the palette. It’s also used for creating texture. In the days of CRT monitors, dithering was especially useful as the screen would actually blur the dithered area and obscure the pattern. Now that crisp LCD monitors are the norm, the patterns are no longer as easy to hide, meaning dithering is not as versatile as it once was. Even so, dithering still has its uses.

The most common form of dithering you’ll see is a 50/50 dither, also known as a 50% dither or a checkerboard pattern.

As shown in the example above, you can create various other patterns to further buffer between a full color and a 50% dithering pattern.
These patterns are often easier to spot than a 50% dither though, so be careful!

Stylized dithering is another technique, and is characterized by the addition of small shapes in the pattern.

Interlaced dithering allows for two dither regions to hug each other. It is called interlaced dithering because the two dithers weave together at the borders. This type of dithering allows you to blend dithers together to form gradients.

Random dithering is a less-common form of dithering, and isn’t generally advised, as it adds a lot of single-pixel noise to the image. While it has some usage in very small doses, random dithering is something you’ll often want to avoid.

As useful as dithering is, it’s often misused by inexperienced artists. Bad dithering is discussed further in the Things to avoid section.


Pixel Clusters:


The cluster of pixels is made from single pixels. However, a single pixel is most of the time near-useless and meaningless if not touching pixels of the same color.
The pixel artist is concerned with the shapes that occur when pixels of similar color touch each other and convey an opaque, flat, shape.
Most of the defeats and possible triumphs of pixel art occur in that exact moment where the artist makes a cluster of pixels.

Ramblethread

I stress the importance of placing individual pixels, but these are rarely independent pixels. A single pixel, isolated, is a speck on a screen- it’s noise. But pixels aren’t usually found alone, instead they exist as part of pixel clusters– groups of pixels of the same color that together produce a solid color field. While the single pixel is our basic building block and smallest unit, the pixel cluster is the unit on which much of our decisions about pixel-placement will be based. And while it’s important to realize individual pixels aren’t independent, it’s just as important to realize pixel clusters aren’t independent. Like puzzle pieces, the borders of a pixel cluster determine the shape of the pixel clusters it borders.
Here is an example of how rearranging the shape of a pixel cluster can have dramatic effects on its neighbor clusters:

While lone pixels often read as noise, a lone pixel of a color different than the field it touches, if used as a buffer (AA), reads as part of that cluster, and is thus unproblematic:

(via Cure on Pixel Joint Forums)

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