The Daily Omnivore

Wood engraving is a technique in printmaking where the ‘matrix’ worked by the artist is a block of wood. It is a variety of woodcut and so a relief printing technique, where ink is applied to the face of the block and printed by using relatively low pressure. A normal engraving, like an etching, has a metal plate as a matrix and is printed by the intaglio method.

Wood engraving traditionally utilizes the end grain of wood as a medium for engraving, while in the older technique of woodcut the softer side grain is used. The technique of wood engraving developed at the end of the 18th century and the beginning of the 19th century, with the works of Thomas Bewick.

Woodcut—formally known as xylography—is a relief printing artistic technique in printmaking in which an image is carved into the surface of a block of wood. the non-printing parts are removed, typically with gouges. The areas to show ‘white’ are cut away with a knife or chisel, leaving the characters or image to show in ‘black’ at the original surface level.

The block is cut along the grain of the wood (unlike wood engraving where the block is cut in the end-grain). Beechwood is commonly used in Europe. Cherry wood is favored in Japan. The surface is covered with ink by rolling over the surface with an ink-covered roller (brayer), leaving ink upon the flat surface but not in the non-printing areas. Multiple colors can be printed by keying the paper to a frame around the woodblocks (where a different block is used for each color).

A compression artifact is a noticeable distortion of media – an image, audio, or video – due to the application of an overly aggressive or inappropriate lossy data compression algorithm. These lossy data compression schemes discard some data to simplify the media sufficiently to store it in the desired space. If there is not enough data in the compressed version to reproduce the original with acceptable fidelity, artifacts will result. Alternatively, the compression algorithm may incorrectly determine certain distortions to be of little subjective importance, but they may in fact be objectionable to the viewer.

Compression artifacts occur in many common media such as DVDs, common computer file formats such as JPEG, MP3, or MPEG files, and Sony’s ATRAC compression algorithm. Uncompressed media (such as on Laserdiscs, Audio CDs, and WAV files) or losslessly compressed media (FLAC, PNG, etc.) do not suffer from compression artifacts. The minimization of artifacts is a key goal in implementation of lossy compression schemes. However, artifacts are occasionally intentionally produced for artistic purposes, a style known as glitch art.