Pixel art

This monster ("The Gunk") is an example of pixel art.

Pixel art is a form of digital art, created through the use of raster graphics software, where images are edited on the pixel level. Graphics in most old (or relatively limited) computer and video games, graphing calculator games, and many mobile phone games are mostly pixel art.

History

The term pixel art was first published by Adele Goldberg and Robert Flegal of Xerox Palo Alto Research Center in 1982. The concept, however, goes back about 10 years before that, for example in Richard Shoup's SuperPaint system in 1972, also at Xerox PARC.

Some traditional art forms, such as cross-stitch, mosaic and beadwork, bear some similarity to pixel art by constructing pictures out of small colored units analogous to the pixels of modern digital computing. A similar concept on a much bigger scale can be seen in the mass games.

Definition

Pixel art is distinguished from other forms of digital art by an insistence upon manual, pixel-level editing of an image (without the application of image filters, automatic anti-aliasing or special rendering modes), often at close magnification. In this form, it is commonly said that "each pixel was placed carefully" to achieve a desired result.

Purists within the pixel art scene hold that "true" pixel art should only be created from tools that place individual pixels (such as the 'pencil' tool), and that pixel artists should avoid all other tools including line, Bezier curve, circle and rectangle. Others counter that tools such as line and bucket-fill are acceptable as their functions could be just as easily, if not as quickly, replicated on an individual pixel basis.

Because of this rule, image filters (such as blurring or alpha-blending) or tools with automatic anti-aliasing are considered not valid tools for pixel art, as such tools calculate new pixel values automatically, contrasting with the precise manual arrangement of pixels associated with pixel art.

Techniques

See also: Spriting

Drawings usually start with what is called the line art, which is the basic line that defines the character, building or anything else the artist is intending to draw. Linearts are usually traced over scanned drawings and are often shared among other pixel artists. Other techniques, some resembling painting, also exist.

The limited palette often implemented into Pixel Art usually promotes the use of dithering in order to achieve different shades and colors, but due to the nature of this form of art this is done completely by hand. Hand-made anti-aliasing is also used.

Here are a few parts of the above image of “The Gunk” in detail, depicting a few of the techniques involved:

Details from The Gunk

1. The basic form of dithering, using two colors in a 2×2 checkerboard pattern. Changing the density of each color will lead to different subtones.

2. Stylized dithering with 2×2 pixel squares randomly scattered can produce interesting textures. Small circles are also frequent.

3. Anti-aliasing can be done, by hand, to smooth curves and transitions. Some artists only do this internally in order to keep crisp outlines that can go over any background. The PNG alpha channel can be used to create external anti-aliasing for any background.

Saving and compression

Pixel art is preferably stored in a file format utilizing lossless data compression, so that each pixel can be stored and retrieved with exact precision. If memory or computational power is limited, run-length encoding is another option, and converting an image to a limited color space, such as an indexed color palette is also very efficient.

GIF and PNG are two file formats commonly used for saving pixel art. Saving pixel art in JPEG format can be detrimental to the work (due to the JPEG's lossy compression algorithm and chroma subsampling). BMP is also avoided, due to its lack of image compression and poor cross-platform support.

GIF file (318 bytes)

PNG file (254 bytes)

JPEG file (706 bytes)

Magnified JPEG to show artifacts

Categories

Isometric

Non-isometric

Pixel art is commonly divided in two subcategories: isometric and non-isometric. The isometric kind is drawn in a near-isometric dimetric projection. This is commonly seen in games to provide a three-dimensional view without using any real three-dimensional processing. Technically, an isometric angle would be of 30 degrees from the horizontal, but this is avoided since the pixels created by a line drawing algorithm would not follow a neat pattern. To fix this, lines with a 1:2 pixel ratio are picked, leading to an angle of, approximately, 26.565 degrees (arctan 0.5).

Non-isometric pixel art is any pixel art that does not fall in the isometric category, such as views from the top, side, front, bottom or perspective views. These are also called Planometric views.

Scaling

Main article: Pixel art scaling algorithms

2x zoom interpolated using the 2xSaI algorithm

When pixel art is displayed at a higher resolution than the source image, it is often scaled using the nearest neighbor interpolation algorithm in order to avoid the blurring caused by other algorithms such as bilinear and bicubic interpolation – which interpolate between adjacent pixels and works best on continuous tones, but not sharp edges or lines; nearest-neighbour interpolation preserves these sharp edges, but it makes diagonal lines and curves look blocky. Thus, hybrid algorithms have been devised to interpolate between continuous tones while preserving the sharpness of lines in the piece; such attempts include the 2xSaI and Super Eagle algorithms.

Uses

Pixel art was very often used in older computer and video console games. With the increasing use of 3D graphics in games, pixel art lost some of its use. Despite that, this is still a very active professional/amateur area, since mobile phones and other portable devices still have low resolution and then require a skillful use of space and memory. Sometimes pixel art is used for advertising too. One such company that uses pixel art to advertise is Bell. The group eboy specializes in pixel graphics for advertising and has been featured in magazines such as Wired, Popular Science, and Fortune 500.

Icons for operating systems with limited graphics abilities are also pixel art. The limited number of colors and resolution presents a challenge when attempting to convey complicated concepts and ideas in an efficient way. On the Microsoft Windows desktop icons are raster images of various sizes, the smaller of which are not necessarily direct scalings of the larger ones and could be considered pixel art. On the GNOME and KDE desktops, icons are represented primarily by SVG images, but with hand-optimised, pixel art PNGs for smaller sizes such as 16x16 and 24x24. Another use of pixel art on modern desktop computers is favicons.

Modern pixel art has been seen as a reaction to the 3D graphics industry by amateur game/graphic hobbyists. Many retro enthusiasts often choose to mimic the style of the past. Some view the pixel art revival as restoring the golden age of second and third generation consoles, where it is argued graphics were more aesthetically pleasing. Pixel art still remains popular and has been used in the virtual world Citypixel as well among handheld devices such as the Nintendo DS and Cellphones.

See also

• Pixel artist
• Dollz, also known as cartoon dolls
• Micro-heroes
• Spriting, making small pixel characters using Pixel art methods.
• Deluxe Paint, a graphics editor for the Amiga frequently used by demoscene pixel artists.
• Microsoft Paint, the raster graphic editor bundled with Microsoft Windows.

External links

Pixelation - Central hub for pixel artists on the internet.

Pixeljoint - Pixel art galleries.